Opinion: Justice Brennan delivered the opinion of the Court.
The Creationism Act forbids the teaching of the theory of evolution in public schools unless accompanied by instruction in "creation science." @ 17:286.4A. No school is required to teach evolution or creation science. If either is taught, however, the other must also be taught. Ibid. The theories of evolution and creation science are statutorily defined as "the scientific evidences for [creation or evolution] and inferences from those scientific evidences." @@ 17.286.3 and.
Appellees, who include parents of children attending Louisiana public schools, Louisiana teachers, and religious leaders, challenged the constitutionality of the Act in District Court, seeking an injunction and declaratory relief (2). Appellants, Louisiana officials charged with implementing the Act, defended on the ground that the purpose of the Act is to protect a legitimate secular interest, namely, academic freedom (3). Appellees attacked the Act as facially invalid because it violated the Establishment Clause and made a motion for summary judgment. The District Court granted the motion. Aguillard v. Treen, 634 F.Supp. 426 (ED La. 1985). The court held that there can be no valid secular reason for prohibiting the teaching of evolution, a theory historically opposed by some religious denominations. The court further concluded that "the teaching of 'creation-science' and 'creationism,' as contemplated by the statute, involves teaching 'tailored to the principles' of a particular religious sect or group of sects." Id., at 427 (citing Epperson v. Arkansas, 393 U.S. 97, 106 (1968)). The District Court therefore held that the Creationism Act violated the Establishment Clause either because it prohibited the teaching of evolution or because it required the teaching of creation science with the purpose of advancing a particular religious doctrine.
The court of Appeals affirmed. 765 F.2d 1251 (CA5 1985). The court observed that the statute's avowed purpose of protecting academic freedom was inconsistent with requiring, upon risk of sanction, the teaching of creation science whenever evolution is taught. Id., at 1257. The court found that the Louisiana Legislature's actual intent was "to discredit evolution by counterbalancing its teaching at every turn with the teaching of creationism, a religious belief." Ibid. Because the Creationism Act was thus a law furthering a particular religious belief, the Court of Appeals held that the Act violated the Establishment Clause. A suggestion for rehearing en banc was denied over a dissent. 778 F.2d 225 (CA5 1985). We noted probable jurisdiction, 476 U.S. 1103 (1986), and now affirm.
In this case, the Court must determine whether the Establishment Clause was violated in the special context of the public elementary and secondary school system. States and local school boards are generally afforded considerable discretion in operating public schools. See Bethel School Dist. No. 403 v. Fraser, 478 U.S. 675, 683 (1986); id., at 687 (BRENNAN, J., concurring in judgment); Tinker v. Des Moines Independent Community School Dist., 393 U.S. 503, 507 (1969). "At the same time . . . we have necessarily recognized that the discretion of the States and local school boards in matters of education must be exercised in a manner that comports with the transcendent imperatives of the First Amendment." Board of Education, Island Trees Union Free School Dist. No. 26 v. Pico, 457 U.S. 853, 864 (1982).
The Court has been particularly vigilant in monitoring compliance with the Establishment Clause in elementary and secondary schools. Families entrust public schools with the education of their children, but condition their trust on the understanding that the classroom will not purposely be used to advance religious views that may conflict with the private beliefs of the student and his or her family. Students in such institutions are impressionable and their attendance is involuntary. See, e. g., Grand Rapids School Dist. v. Ball, 473 U.S. 373, 383 (1985); Wallace v. Jaffree, 472 U.S. 38, 60, n. 51 (1985); Meek v. Pittenger, 421 U.S. 349, 369 (1975); Abington School Dist. v. Schempp, 374 U.S. 203, 252-253 (1963) (BRENNAN, J., concurring). The State exerts great authority and coercive power through mandatory attendance requirements, and because of the students' emulation of teachers as role models and the children's susceptibility to peer pressure.
See Bethel School Dist. No. 403 v. Fraser, supra, at 683; Wallace v. Jaffree, supra, at 81 (O'CONNOR, J., concurring in judgment). Furthermore, "the public school is at once the symbol of our democracy and the most pervasive means for promoting our common destiny. In no activity of the State is it more vital to keep out divisive forces than in its schools . . . ." Illinois ex rel. McCollum v. Board of Education, 333 U.S. 203, 231 (1948) (opinion of Frankfurter, J.).
Consequently, the Court has been required often to invalidate statutes which advance religion in public elementary and secondary schools. See, e. g., Grand Rapids School Dist. v. Ball, supra (school district's use of religious school teachers in public schools); Wallace v. Jaffree, supra (Alabama statute authorizing moment of silence for school prayer); Stone v. Graham, 449 U.S. 39 (1980) (posting copy of Ten Commandments on public classroom wall); Epperson v. Arkansas, 393 U.S. 97 (1968) (statute forbidding teaching of evolution); Abington School Dist. v. Schempp, supra (daily reading of Bible); Engel v. Vitale, 370 U.S. 421, 430 (1962) (recitation of "denominationally neutral" prayer).
Therefore, in employing the three-pronged Lemon test, we must do so mindful of the particular concerns that arise in the context of public elementary and secondary schools. We now turn to the evaluation of the Act under the Lemon test.
True, the Act's stated purpose is to protect academic freedom. La. Rev. Stat. Ann. @ 17:286.2 (West 1982). This phrase might, in common parlance, be understood as referring to enhancing the freedom of teachers to teach what they will. The Court of Appeals, however, correctly concluded that the Act was not designed to further that goal. We find no merit in the State's argument that the "legislature may not [have] used the terms 'academic freedom' in the correct legal sense. They might have [had] in mind, instead, a basic concept of fairness; teaching all of the evidence." Tr. of Oral Arg. 60. Even if "academic freedom" is read to mean "teaching all of the evidence" with respect to the origin of human beings, the Act does not further this purpose. The goal of providing a more comprehensive science curriculum is not furthered either by outlawing the teaching of evolution or by requiring the teaching of creation science.
It is equally clear that requiring schools to teach creation science with evolution does not advance academic freedom. The Act does not grant teachers a flexibility that they did not already possess to supplant the present science curriculum with the presentation of theories, besides evolution, about the origin of life. Indeed, the Court of Appeals found that no law prohibited Louisiana public school teachers from teaching any scientific theory. 765 F.2d, at 1257. As the president of the Louisiana Science Teachers Association testified, "any scientific concept that's based on established fact can be included in our curriculum already, and no legislation allowing this is necessary." 2 App. E-616. The Act provides Louisiana schoolteachers with no new authority. Thus the stated purpose is not furthered by it.
The Alabama statute held unconstitutional in Wallace v. Jaffree, supra, is analogous. In Wallace, the State characterized its new law as one designed to provide a 1-minute period for meditation. We rejected that stated purpose as insufficient, because a previously adopted Alabama law already provided for such a 1-minute period. Thus, in this case, as in Wallace, "appellants have not identified any secular purpose that was not fully served by [existing state law] before the enactment of [the statute in question]." 472 U.S., at 59.
Furthermore, the goal of basic "fairness" is hardly furthered by the Act's discriminatory preference for the teaching of creation science and against the teaching of evolution. While requiring that curriculum guides be developed for creation science, the Act says nothing of comparable guides for evolution. La. Rev. Stat. Ann. @ 17:286.7A (West 1982). Similarly, resource services are supplied for creation science but not for evolution. @ 17:286.7B. Only "creation scientists" can serve on the panel that supplies the resource services. Ibid. The Act forbids school boards to discriminate against anyone who "chooses to be a creation-scientist" or to teach "creationism," but fails to protect those who choose to teach evolution or any other noncreation science theory, or who refuse to teach creation science. @ 17:286.4C.
If the Louisiana Legislature's purpose was solely to maximize the comprehensiveness and effectiveness of science instruction, it would have encouraged the teaching of all scientific theories about the origins of humankind. But under the Act's requirements, teachers who were once free to teach any and all facets of this subject are now unable to do so. Moreover, the Act fails even to ensure that creation science will be taught, but instead requires the teaching of this theory only when the theory of evolution is taught. Thus we agree with the Court of Appeals' conclusion that the Act does not serve to protect academic freedom, but has the distinctly different purpose of discrediting "evolution by counterbalancing its teaching at every turn with the teaching of creationism . . . ." 765 F.2d, at 1257.
As in Stone and Abington, we need not be blind in this case to the legislature's preeminent religious purpose in enacting this statute. There is a historic and contemporaneous link between the teachings of certain religious denominations and the teaching of evolution. It was this link that concerned the Court in Epperson v. Arkansas, 393 U.S. 97 (1968), which also involved a facial challenge to a statute regulating the teaching of evolution. In that case, the Court reviewed an Arkansas statute that made it unlawful for an instructor to teach evolution or to use a textbook that referred to this scientific theory. Although the Arkansas antievolution law did not explicitly state its predominate religious purpose, the Court could not ignore that "the statute was a product of the upsurge of 'fundamentalist' religious fervor" that has long viewed this particular scientific theory as contradicting the literal interpretation of the Bible. Id., at 98, 106-107. After reviewing the history of antievolution statutes, the Court determined that "there can be no doubt that the motivation for the [Arkansas] law was the same [as other anti-evolution statutes]: to suppress the teaching of a theory which, it was thought, 'denied' the divine creation of man." Id., at 109. The Court found that there can be no legitimate state interest in protecting particular religions from scientific views "distasteful to them," id., at 107 (citation omitted), and concluded "that the First Amendment does not permit the State to require that teaching and learning must be tailored to the principles or prohibitions of any religious sect or dogma," id., at 106.
These same historic and contemporaneous antagonisms between the teachings of certain religious denominations and the teaching of evolution are present in this case. The preeminent purpose of the Louisiana Legislature was clearly to advance the religious viewpoint that a supernatural being created humankind. The term "creation science" was defined as embracing this particular religious doctrine by those responsible for the passage of the Creationism Act. Senator Keith's leading expert on creation science, Edward Boudreaux, testified at the legislative hearings that the theory of creation science included belief in the existence of a supernatural creator. See 1 App. E-421 -- E-422 (noting that "creation scientists" point to high probability that life was "created by an intelligent mind"). Senator Keith also cited testimony from other experts to support the creation-science view that "a creator [was] responsible for the universe and everything in it." 2 App. E-497. The legislative history therefore reveals that the term "creation science," as contemplated by the legislature that adopted this Act, embodies the religious belief that a supernatural creator was responsible for the creation of humankind.
Furthermore, it is not happenstance that the legislature required the teaching of a theory that coincided with this religious view. The legislative history documents that the Act's primary purpose was to change the science curriculum of public schools in order to provide persuasive advantage to a particular religious doctrine that rejects the factual basis of evolution in its entirety. The sponsor of the Creationism Act, Senator Keith, explained during the legislative hearings that his disdain for the theory of evolution resulted from the support that evolution supplied to views contrary to his own religious beliefs. According to Senator Keith, the theory of evolution was consonant with the "cardinal principle[s] of religious humanism, secular humanism, theological liberalism, aetheistism [sic]." 1 App. E-312 -- E-313; see also 2 App. E-499 -- E-500. The state senator repeatedly stated that scientific evidence supporting his religious views should be included in the public school curriculum to redress the fact that the theory of evolution incidentally coincided with what he characterized as religious beliefs antithetical to his own. The legislation therefore sought to alter the science curriculum to reflect endorsement of a religious view that is antagonistic to the theory of evolution.
In this case, the purpose of the Creationism Act was to restructure the science curriculum to conform with a particular religious viewpoint. Out of many possible science subjects taught in the public schools, the legislature chose to affect the teaching of the one scientific theory that historically has been opposed by certain religious sects. As in Epperson, the legislature passed the Act to give preference to those religious groups which have as one of their tenets the creation of humankind by a divine creator. The "overriding fact" that confronted the Court in Epperson was "that Arkansas' law selects from the body of knowledge a particular segment which it proscribes for the sole reason that it is deemed to conflict with . . . a particular interpretation of the Book of Genesis by a particular religious group." 393 U.S., at 103. Similarly, the Creationism Act is designed either to promote the theory of creation science which embodies a particular religious tenet by requiring that creation science be taught whenever evolution is taught or to prohibit the teaching of a scientific theory disfavored by certain religious sects by forbidding the teaching of evolution when creation science is not also taught. The Establishment Clause, however, "forbids alike the preference of a religious doctrine or the prohibition of theory which is deemed antagonistic to a particular dogma." Id., at 106-107 (emphasis added). Because the primary purpose of the Creationism Act is to advance a particular religious belief, the Act endorses religion in violation of the First Amendment.
We do not imply that a legislature could never require that scientific critiques of prevailing scientific theories be taught. Indeed, the Court acknowledged in Stone that its decision forbidding the posting of the Ten Commandments did not mean that no use could ever be made of the Ten Commandments, or that the Ten Commandments played an exclusively religious role in the history of Western Civilization. 449 U.S., at 42. In a similar way, teaching a variety of scientific theories about the origins of humankind to schoolchildren might be validly done with the clear secular intent of enhancing the effectiveness of science instruction. But because the primary purpose of the Creationism Act is to endorse a particular religious doctrine, the Act furthers religion in violation of the Establishment Clause.
In this case, appellees' motion for summary judgment rested on the plain language of the Creationism Act, the legislative history and historical context of the Act, the specific sequence of events leading to the passage of the Act, the State Board's report on a survey of school superintendents, and the correspondence between the Act's legislative sponsor and its key witnesses. Appellants contend that affidavits made by two scientists, two theologians, and an education administrator raise a genuine issue of material fact and that summary judgment was therefore barred. The affidavits define creation science as "origin through abrupt appearance in complex form" and allege that such a viewpoint constitutes a true scientific theory. See App. to Brief for Appellants A-7 to A-40.
We agree with the lower courts that these affidavits do not raise a genuine issue of material fact. The existence of "uncontroverted affidavits" does not bar summary judgment. Moreover, the postenactment testimony of outside experts is of little use in determining the Louisiana Legislature's purpose in enacting this statute. The Louisiana Legislature did hear and rely on scientific experts in passing the bill (18), but none of the persons making the affidavits produced by the appellants participated in or contributed to the enactment of the law or its implementation (19). The District Court, in its discretion, properly concluded that a Monday-morning "battle of the experts" over possible technical meanings of terms in the statute would not illuminate the contemporaneous purpose of the Louisiana Legislature when it made the law (21).
CONCUR BY: POWELL; WHITE
 Justice O'connor joins all but Part II of this opinion
 Appellants, the Louisiana Governor, the Attorney General, the State Superintendent, the State Department of Education and the St. Tammany Parish School Board, agreed not to implement the Creationism Act pending the final outcome of this litigation. The Louisiana Board of Elementary and Secondary Education, and the Orleans Parish School Board were among the original defendants in the suit but both later realigned as plaintiffs.
 The District Court initially stayed the action pending the resolution of a separate lawsuit brought by the Act's legislative sponsor and others for declaratory and injunctive relief. After the separate suit was dismissed on jurisdictional grounds, Keith v. Louisiana Department of Education, 553 F.Supp. 295 (MD La. 1982), the District Court lifted its stay in this case and held that the Creationism Act violated the Louisiana Constitution. The court ruled that the State Constitution grants authority over the public school system to the Board of Elementary and Secondary Education rather than the state legislature. On appeal, the Court of Appeals certified the question to the Louisiana Supreme Court, which found the Creationism Act did not violate the State Constitution, Aguillard v. Treen, 440 So. 2d 704 (1983). The Court of Appeals then remanded the case to the District Court to determine whether the Creationism Act violates the Federal Constitution. Aguillard v. Treen, 720 F.2d 676 (CA5 1983).
 The First Amendment states: "Congress shall make no law respecting an establishment of religion . . . ." Under the Fourteenth Amendment, this "fundamental concept of liberty" applies to the States. Cantwell v. Connecticut, 310 U.S. 296, 303 (1940).
 The Lemon test has been applied in all cases since its adoption in 1971, except in Marsh v. Chambers, 463 U.S. 783 (1983), where the Court held that the Nebraska Legislature's practice of opening a session with a prayer by a chaplain paid by the State did not violate the Establishment Clause. The Court based its conclusion in that case on the historical acceptance of the practice. Such a historical approach is not useful in determining the proper roles of church and state in public schools, since free public education was virtually nonexistent at the time the Constitution was adopted. See Wallace v. Jaffree, 472 U.S. 38, 80 (1985) (O'CONNOR, J., concurring in judgment) (citing Abington School Dist. v. Schempp, 374 U.S. 203, 238, and n. 7 (1963) (BRENNAN, J., concurring)).
 The potential for undue influence is far less significant with regard to college students who voluntarily enroll in courses. "This distinction warrants a difference in constitutional results." Abington School Dist. v. Schempp, supra, at 253 (BRENNAN, J., concurring). Thus, for instance, the Court has not questioned the authority of state colleges and universities to offer courses on religion or theology. See Widmar v. Vincent, 454 U.S. 263, 271 (1981) (POWELL, J.); id., at 281 (STEVENS, J., concurring in judgment).
 The Court of Appeals stated that "academic freedom embodies the principle that individual instructors are at liberty to teach that which they deem to be appropriate in the exercise of their professional judgment." 765 F.2d, at 1257. But, in the State of Louisiana, courses in public schools are prescribed by the State Board of Education and teachers are not free, absent permission, to teach courses different from what is required. Tr. of Oral Arg. 44-46. "Academic freedom," at least as it is commonly understood, is not a relevant concept in this context. Moreover, as the Court of Appeals explained, the Act "requires, presumably upon risk of sanction or dismissal for failure to comply, the teaching of creation-science whenever evolution is taught. Although states may prescribe public school curriculum concerning science instruction under ordinary circumstances, the compulsion inherent in the Balanced Treatment Act is, on its face, inconsistent with the idea of academic freedom as it is universally understood." 765 F.2d, at 1257 (emphasis in original). The Act actually serves to diminish academic freedom by removing the flexibility to teach evolution without also teaching creation science, even if teachers determine that such curriculum results in less effective and comprehensive science instruction.
 Creationism Act's provisions appear among other provisions prescribing the courses of study in Louisiana's public schools. These other provisions, similar to those in other States, prescribe courses of study in such topics as driver training, civics, the Constitution, and free enterprise. None of these other provisions, apart from those associated with the Creationism Act, nominally mandates "equal time" for opposing opinions within a specific area of learning. See, e. g., La. Rev. Stat. Ann. @@ 17:261-17:281 (West 1982 and Supp. 1987).
 The dissent concludes that the Act's purpose was to protect the academic freedom of students, and not that of teachers. Post, at 628. Such a view is not at odds with our conclusion that if the Act's purpose was to provide comprehensive scientific education (a concern shared by students and teachers, as well as parents), that purpose was not advanced by the statute's provisions. Supra, at 587.
Moreover, it is astonishing that the dissent, to prove its assertion, relies on a section of the legislation that was eventually deleted by the legislature. Compare @ 3702 in 1 App. E-292 (text of section prior to amendment) with La. Rev. Stat. Ann. @ 17:286.2 (West 1982). The dissent contends that this deleted section -- which was explicitly rejected by the Louisiana Legislature -- reveals the legislature's "obviously intended meaning of the statutory terms 'academic freedom.'" Post, at 628. Quite to the contrary, Boudreaux, the main expert relied on by the sponsor of the Act, cautioned the legislature that the words "academic freedom" meant "freedom to teach science." 1 App. E-429. His testimony was given at the time the legislature was deciding whether to delete this section of the Act.
 See McLean v. Arkansas Bd. of Ed., 529 F.Supp. 1255, 1258-1264 (ED Ark. 1982) (reviewing historical and contemporary antagonisms between the theory of evolution and religious movements).
 The Court evaluated the statute in light of a series of antievolution statutes adopted by state legislatures dating back to the Tennessee statute that was the focus of the celebrated Scopes trial in 1925. Epperson v. Arkansas, 393 U.S., at 98, 101, n. 8, and 109. The Court found the Arkansas statute comparable to this Tennessee "monkey law," since both gave preference to "'religious establishments which have as one of their tenets or dogmas the instantaneous creation of man.'" Id., at 103, n. 11 (quoting Scopes v. State, 154 Tenn. 105, 126, 289 S. W. 363, 369 (1927) (Chambliss, J., concurring)).
 While the belief in the instantaneous creation of humankind by a supernatural creator may require the rejection of every aspect of the theory of evolution, an individual instead may choose to accept some or all of this scientific theory as compatible with his or her spiritual outlook. See Tr. of Oral Arg. 23-29.
 Boudreaux repeatedly defined creation science in terms of a theory that supports the existence of a supernatural creator. See, e. g., 2 App. E-501 -- E-502 (equating creation science with a theory pointing "to conditions of a creator"); 1 App. E-153 -- E-154 ("Creation . . . requires the direct involvement of a supernatural intelligence"). The lead witness at the hearings introducing the original bill, Luther Sunderland, described creation science as postulating "that everything was created by some intelligence or power external to the universe." Id., at E-9 -- E-10.
14 Senator Keith believed that creation science embodied this view: "One concept is that a creator however you define a creator was responsible for everything that is in this world. The other concept is that it just evolved." Id., at E-280. Besides Senator Keith, several of the most vocal legislators also revealed their religious motives for supporting the bill in the official legislative history. See, e. g., id., at E-441, E-443 (Sen. Saunders noting that bill was amended so that teachers could refer to the Bible and other religious texts to support the creation-science theory); 2 App. E-561 -- E-562, E-610 (Rep. Jenkins contending that the existence of God was a scientific fact).
 See, e. g., 1 App. E-74 -- E-75 (noting that evolution is contrary to his family's religious beliefs); id., at E-313 (contending that evolution advances religions contrary to his own); id., at E-357 (stating that evolution is "almost a religion" to science teachers); id., at E-418 (arguing that evolution is cornerstone of some religions contrary to his own); 2 App. E-763 -- E-764 (author of model bill, from which Act is derived, sent copy of the model bill to Senator Keith and advised that "I view this whole battle as one between God and anti-God forces . . . . If evolution is permitted to continue . . . it will continue to be made to appear that a Supreme Being is unnecessary . . .").
 Neither the District Court nor the Court of Appeals found a clear secular purpose, while both agreed that the Creationism Act's primary purpose was to advance religion. "When both courts below are unable to discern an arguably valid secular purpose, this Court normally should hesitate to find one." Wallace v. Jaffree, 472 U.S., at 66 (POWELL, J., concurring).
 There is "no express or implied requirement in Rule 56 that the moving party support its motion with affidavits or other similar materials negating the opponent's claim." Celotex Corp. v. Catrett, 477 U.S. 317, 323 (1986) (emphasis in original).