with whom Justice O’Connor joins, concurring.
I write separately to note certain aspects of the legislative history, and to emphasize that nothing in the Court’s opinion diminishes the traditionally broad discretion accorded state and local school officials in the selection of the public school curriculum.
I
This Court consistently has applied the three-pronged test of Lemon v. Kurtzman, 403 U. S. 602 (1971), to determine whether a particular state action violates the Establishment Clause of the Constitution.1 See, e. g., Grand Rapids School Dist. v. Ball, 473 U. S. 373, 383 (1985) (“We have particularly relied on Lemon in every case involving the sensitive relationship between government and religion in the education of our children”). The first requirement of the Lemon test is that the challenged statute have a “secular legislative purpose.” Lemon v. Kurtzman, supra, at 612. See Committee for Public Education & Religious Liberty v. Nyquist, 413 U. S. 756, 773 (1973). If no valid secular purpose can be identified, then the statute violates the Establishment Clause.
A
“The starting point in every case involving construction of a statute is the language itself.” Blue Chip Stamps v. Manor Drug Stores, 421 U. S. 723, 756 (1975) (Powell, J., *598concurring). The Balanced Treatment for Creation-Science and Evolution-Science Act (Act or Balanced Treatment Act), La. Rev. Stat. Ann. §17:286.1 et seq. (West 1982), provides in part:
“[P]ublic schools within [the] state shall give balanced treatment to creation-science and to evolution-science. Balanced treatment of these two models shall be given in classroom lectures taken as a whole for each course, in textbook materials taken as a whole for each course, in library materials taken as a whole for the sciences and taken as a whole for the humanities, and in other educational programs in public schools, to the extent that such lectures, textbooks, library materials, or educational programs deal in any way with the subject of the origin of man, life, the earth, or the universe. When creation or evolution is taught, each shall be taught as a theory, rather than as proven scientific fact.” § 17:286.4(A).
“Balanced treatment” means “providing whatever information and instruction in both creation and evolution models the classroom teacher determines is necessary and appropriate to provide insight into both theories in view of the textbooks and other instructional materials available for use in his classroom.” §17:286.3(1). “Creation-science” is defined as “the scientific evidences for creation and inferences from those scientific evidences.” §17:286.3(2). “Evolution-science” means “the scientific evidences for evolution and inferences from those scientific evidences.” §17:286.3(3).
Although the Act requires the teaching of the scientific evidences of both creation and evolution whenever either is taught, it does not define either term. “A fundamental canon of statutory construction is that, unless otherwise defined, words will be interpreted as taking their ordinary, contemporary, common meaning.” Perrin v. United States, 444 U. S. 37, 42 (1979). The “doctrine or theory of creation” is commonly defined as “holding that matter, the various forms of life, and the world were created by a transcendent God out *599of nothing.” Webster’s Third New International Dictionary 532 (unabridged 1981). “Evolution” is defined as “the theory that the various types of animals and plants have their origin in other preexisting types, the distinguishable differences being due to modifications in successive generations.” Id., at 789. Thus, the Balanced Treatment Act mandates that public schools present the scientific evidence to support a theory of divine creation whenever they present the scientific evidence to support the theory of evolution. “[CJoncepts concerning God or a supreme being of some sort are manifestly religious .... These concepts do not shed that religiosity merely because they are presented as a philosophy or as a science.” Malnak v. Yogi, 440 F. Supp. 1284, 1322 (NJ 1977), aff’d per curiam, 592 F. 2d 197 (CA3 1979). From the face of the statute, a purpose to advance a religious belief is apparent.
A religious purpose alone is not enough to invalidate an act of a state legislature. The religious purpose must predominate. See Wallace v. Jaffree, 472 U. S. 38, 56 (1985); id., at 64 (Powell, J., concurring); Lynch v. Donnelly, 465 U. S. 668, 681, n. 6 (1984). The Act contains a statement of purpose: to “protec[t] academic freedom.” § 17:286.2. This statement is puzzling. Of course, the “academic freedom” of teachers to present information in public schools, and students to receive it, is broad. But it necessarily is circumscribed by the Establishment Clause. “Academic freedom” does not encompass the right of a legislature to structure the public school curriculum in order to advance a particular religious belief. Epperson v. Arkansas, 393 U. S. 97, 106 (1968). Nevertheless, I read this statement in the Act as rendering the purpose of the statute at least ambiguous. Accordingly, I proceed to review the legislative history of the Act.
B
In June 1980, Senator Bill Keith introduced Senate Bill 956 in the Louisiana Legislature. The stated purpose of the bill *600was to “assure academic freedom by requiring the teaching of the theory of creation ex nihilo in all public schools where the theory of evolution is taught.” 1 App. E-l.2 The bill defined the “theory of creation ex nihilo” as “the belief that the origin of the elements, the galaxy, the solar system, of life, of all the species of plants and animals, the origin of man, and the origin of all things and their processes and relationships were created ex nihilo and fixed by God.” Id., at E-la— E-lb. This theory was referred to by Senator Keith as “scientific creationism.” Id., at E-2.
While a Senate committee was studying scientific creationism, Senator Keith introduced a second draft of the bill, requiring balanced treatment of “evolution-science” and “creation-science.” Id., at E-108. Although the Keith bill prohibited “instruction in any religious doctrine or materials,” id., at E-302, it defined “creation-science” to include
“the scientific evidences and related inferences that indicate (a) sudden creation of the universe, energy, and life from nothing; (b) the insufficiency of mutation and natural selection in bringing about development of all living kinds from a single organism; (c) changes only within fixed limits or originally created kinds of plants and animals; (d) separate ancestry for man and apes; (e) explanation of the earth’s geology by catastrophism, including the occurrence of a worldwide flood; and (f) a *601relatively recent inception of the earth and living kinds.” Id., at E-298 — E-299.
Significantly, the model Act on which the Keith bill relied was also the basis for a similar statute in Arkansas. See McLean v. Arkansas Board of Education, 529 F. Supp. 1255 (ED Ark. 1982). The District Court in McLean carefully examined this model Act, particularly the section defining creation science, and concluded that “[b]oth [its] concepts and wording. . . convey an inescapable religiosity.” Id., at 1265. The court found that “[t]he ideas of [this section] are not merely similar to the literal interpretation of Genesis; they are identical and parallel to no other story of creation.” Ibid.
The complaint in McLean was filed on May 27, 1981. On May 28, the Louisiana Senate committee amended the Keith bill to delete the illustrative list of scientific evidences. According to the legislator who proposed the amendment, it was “not intended to try to gut [the bill] in any way, or defeat the purpose [for] which Senator Keith introduced [it],” 1 App. E-432, and was not viewed as working “any violence to the bill.” Id., at E-438. Instead, the concern was “whether this should be an all inclusive list.” Ibid.
The legislature then held hearings on the amended bill that became the Balanced Treatment Act under review. The principal creation scientist to testify in support of the Act was Dr. Edward Boudreaux. He did not elaborate on the nature of creation science except to indicate that the “scientific evidences” of the theory are “the objective information of science [that] point[s] to conditions of a creator.” 2 id., at E-501 — E-502. He further testified that the recognized creation scientists in the United States, who “numbe[r] something like a thousand [and] who hold doctorate and masters degrees in all areas of science,” are affiliated with either or both the Institute for Creation Research and the Creation Research Society. Id., at E-503 — E-504. Information on both of these organizations is part of the legislative history, *602and a review of their goals and activities sheds light on the nature of creation science as it was presented to, and understood by, the Louisiana Legislature.
The Institute for Creation Research is an affiliate of the Christian Heritage College in San Diego, California. The Institute was established to address the “urgent need for our nation to return to belief in a personal, omnipotent Creator, who has a purpose for His creation and to whom all people must eventually give account.” 1 id., at E-197. A goal of the Institute is “a revival of belief in special creation as the true explanation of the origin of the world.” Therefore, the Institute currently is working on the “development of new methods for teaching scientific creationism in public schools.” Id., at E-197 — E-199. The Creation Research Society (CRS) is located in Ann Arbor, Michigan. A member must subscribe to the following statement of belief: “The Bible is the written word of God, and because it is inspired throughout, all of its assertions are historically and scientifically true.” 2 id., at E-583. To study creation science at the CRS, a member must accept “that the account of origins in Genesis is a factual presentation of simple historical truth.” Ibid.3
*603C
When, as here, “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). My examination of the language and the legislative history of the Balanced Treatment Act confirms that the intent of the Louisiana Legislature was to promote a particular religious belief. The legislative history of the Arkansas statute prohibiting the teaching of evolution examined in Epperson v. Arkansas, 393 U. S. 97 (1968), was strikingly similar to the legislative history of the Balanced Treatment Act. In Epperson, the Court found:
“It is clear that fundamentalist sectarian conviction was and is the law’s reason for existence. Its antecedent, Tennessee’s ‘monkey law,’ candidly stated its purpose: to make it unlawful ‘to teach any theory that denies the story of the Divine Creation of man as taught in the Bible, and to teach instead that man has descended from a lower order of animals.’ Perhaps the sensational publicity attendant upon the Scopes trial induced Arkansas to adopt less explicit language. It eliminated Tennessee’s reference to. ‘the story of the Divine' creation of man’ as taught in the Bible, but there is no doubt that the motivation for the law was the same: to suppress the teaching of a theory which, it was thought, ‘denied’ the divine creation of man.” Id., at 107-109 (footnotes omitted).
Here, it is clear that religious belief is the Balanced Treatment Act’s “reason for existence.” The tenets of creation science parallel the Genesis story of creation,4 and this is a *604religious belief. “[N]o legislative recitation of a supposed secular purpose can blind us to that fact.” Stone v. Graham, 449 U. S. 39, 41 (1980). Although the Act as finally enacted does not contain explicit reference to its religious purpose, there is no indication in the legislative history that the deletion of “creation ex nihilo” and the four primary tenets of the theory was intended to alter the purpose of teaching creation science. Instead, the statements of purpose of the sources of creation science in the United States make clear that their purpose is to promote a religious belief. I find no persuasive evidence in the legislative history that the legislature’s purpose was any different. The fact that the Louisiana Legislature purported to add information to the school curriculum rather than detract from it as in Epperson does not affect my analysis. Both legislatures acted with the unconstitutional purpose of structuring the public school curriculum to make it compatible with a particular religious belief: the “divine creation of man.”
That the statute is limited to the scientific evidences supporting the theory does not render its purpose secular. In reaching its conclusion that the Act is unconstitutional, the Court of Appeals “[did] not deny that the underpinnings of creationism may be supported by scientific evidence.” 765 F. 2d 1251, 1256 (1985). And there is no need to do so. Whatever the academic merit of particular subjects or theories, the Establishment Clause limits the discretion of state officials to pick and choose among them for the purpose of promoting a particular religious belief. The language of the statute and its legislative history convince me that the Louisiana Legislature exercised its discretion for this purpose in this case.
*605I — I
Even though I find Louisiana’s Balanced Treatment Act unconstitutional, I adhere to the view “that the States and locally elected school boards should have the responsibility for determining the educational policy of the public schools.” Board of Education, Island Trees Union Free School Dist. No. 26 v. Pico, 457 U. S. 853, 893 (1982) (Powell, J., dissenting) . A decision respecting the subj ect matter to be taught in public schools does not violate the Establishment Clause simply because the material to be taught “ ‘happens to coincide or harmonize with the tenets of some or all religions.’” Harris v. McRae, 448 U. S. 297, 319 (1980) (quoting McGowan v. Maryland, 366 U. S. 420, 442 (1961)). In the context of a challenge under the Establishment Clause, interference with the decisions of these authorities is warranted only when the purpose for their decisions is clearly religious.
The history of the Religion Clauses of the First Amendment has been chronicled by this Court in detail. See, e. g., Everson v. Board of Education, 330 U. S. 1, 8-14 (1947); Engel v. Vitale, 370 U. S. 421, 425-430 (1962); McGowan v. Maryland, supra, at 437-442. Therefore, only a brief review at this point may be appropriate. The early settlers came to this country from Europe to escape religious persecution that took the form of forced support of state-established churches. The new Americans thus reacted strongly when they perceived the same type of religious intolerance emerging in this country. The reaction in Virginia, the home of many of the Founding Fathers, is instructive. George Mason’s draft of the Virginia Declaration of Rights was adopted by the House of Burgesses in 1776. Because of James Madison’s influence, the Declaration of Rights embodied the guarantee of free exercise of religion, as opposed to toleration. Eight years later, a provision prohibiting the establishment of religion became a part of Virginia law when James Madison’s Memorial and Remonstrance against Re*606ligious Assessments, written in response to a proposal that all Virginia citizens be taxed to support the teaching of the Christian religion, spurred the legislature to consider and adopt Thomas Jefferson’s Bill for Establishing Religious Freedom. See Committee for Public Education & Religious Liberty v. Nyquist, 413 U. S., at 770, n. 28. Both the guarantees of free exercise and against the establishment of religion were then incorporated into the Federal Bill of Rights by its drafter, James Madison.
While the “meaning and scope of the First Amendment” must be read “in light of its history and the evils it was designed forever to suppress,” Everson v. Board of Education, supra, at 14-15, this Court has also recognized that “this Nation’s history has not been one of entirely sanitized separation between Church and State.” Committee for Public Education & Religious Liberty v. Nyquist, supra, at 760. “The fact that the Founding Fathers believed devotedly that there was a God and that the unalienable rights of man were rooted in Him is clearly evidenced in their writings, from the Mayflower Compact to the Constitution itself.” Abington School District v. Schempp, 374 U. S. 203, 213 (1963).5 The Court properly has noted “an unbroken history of official acknowledgment... of the role of religion in American life.” Lynch v. Donnelly, 465 U. S., at 674, and has recognized that these references to “our religious heritage” are constitutionally acceptable. Id., at 677.
As a matter of history, schoolchildren can and should properly be informed of all aspects of this Nation’s religious heritage. I would see no constitutional problem if schoolchildren were taught the nature of the Founding Father’s religious beliefs and how these beliefs affected the attitudes *607of the times and the structure of our government.6 Courses in comparative religion of course are customary and constitutionally appropriate.7 In fact, since religion permeates our history, a familiarity with the nature of religious beliefs is necessary to understand many historical as well as contemporary events.8 In addition, it is worth noting that the Estab*608lishment Clause does not prohibit per se the educational use of religious documents in public school education. Although this Court has recognized that the Bible is “an instrument of religion,” Abington School District v. Schempp, supra, at 224, it also has made clear that the Bible “may constitutionally be used in an appropriate study of history, civilization, ethics, comparative religion, or the like.” Stone v. Graham, 449 U. S., at 42 (citing Abington School District v. Schempp, supra, at 225). The book is, in fact, “the world’s all-time best seller”9 with undoubted literary and historic value apart from its religious content. The Establishment Clause is properly understood to prohibit the use of the Bible and other religious documents in public school education only when the purpose of the use is to advance a particular religious belief.
i — i 1 — 1 I — I
In sum, I find that the language and the legislative history of the Balanced Treatment Act unquestionably demonstrate that its purpose is to advance a particular religious belief. Although the discretion of state and local authorities over public school curricula is broad, “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.” Epperson v. Arkansas, 393 U. S., at 106. Accordingly, I concur in the opinion of the Court and its judgment that the Balanced Treatment Act violates the Establishment Clause of the Constitution.
As the Court recognizes, ante, at 583, n. 4, the one exception to this consistent application of the Lemon test is Marsh v. Chambers, 463 U. S. 783 (1983).
Creation “ex nihilo” means creation “from nothing” and has been found to be an “inherently religious concept.” McLean v. Arkansas Board of Education, 529 F. Supp. 1255, 1266 (ED Ark. 1982). The District Court in McLean found:
“The argument that creation from nothing in [§] 4(a)(1) [of the substantially similar Arkansas Balanced Treatment Act] does not involve a supernatural deity has no evidentiary or rational support. To the contrary, ‘creation out of nothing’ is a concept unique to Western religions. In traditional Western religious thought, the conception of a creator of the world is a conception of God. Indeed, creation of the world ‘out of nothing’ is the ultimate religious statement because God is the only actor.” Id., at 1265.
The District Court in McLean noted three other elements of the CRS statement of belief to which members must subscribe:
“ ‘[i] All basic types of living things, including man, were made by direct creative acts of God during Creation Week as described in Genesis. Whatever biological changes have occurred since Creation have accomplished only changes within the original created kinds, [ii] The great Flood described in Genesis, commonly referred to as the Noachian Deluge, was an historical event, world-wide in its extent and effect, [iii] Finally, we are an organization of Christian men of science, who accept Jesus Christ as our Lord and Savior. The account of the special creation of Adam and Eve as one man and one woman, and their subsequent Fall into sin, is the basis for our belief in the necessity of a Savior for all mankind. Therefore, salvation can come only thru (sic) accepting Jesus Christ as our Savior.’ ” 529 F. Supp., at 1260, n. 7.
After hearing testimony from numerous experts, the District Court in McLean concluded that “[t]he parallels between [the definition section of the model Act] and Genesis are quite specific.” Id., at 1265, n. 19. It found the concepts of “sudden creation from nothing,” a worldwide flood of divine origin, and “kinds” to be derived from Genesis; “relatively recent inception” to mean “an age of the earth from 6,000 to 10,000 years” and to *604be based “on the genealogy of the Old Testament using the rather astronomical ages assigned to the patriarchs”; and the “separate ancestry of man and ape” to focus on “the portion of the theory of evolution which Fundamentalists find most offensive.” Ibid, (citing Epperson v. Arkansas, 393 U. S. 97 (1968)).
John Adams wrote to Thomas Jefferson: “[T]he Bible is the best book in the world. It contains more of my little philosophy than all the libraries I have seen; and such parts of it as I cannot reconcile to my little philosophy, I postpone for future investigation.” Letter of Dec. 25, 1813, 10 Works of John Adams 85 (1856).
There is an enormous variety of religions in the United States. The Encyclopedia of American Religions (2d ed. 1987) describes 1,347 religious organizations. The United States Census Bureau groups the major American religions into: Buddhist Churches of America; Eastern Churches; Jews; Old Catholic, Polish National Catholic, and Armenian Churches; The Roman Catholic Church; Protestants; and Miscellaneous. Statistical Abstract of the United States 50 (106th ed. 1986).
Our country has become strikingly multireligious as well as multiracial and multiethnic. This fact, perhaps more than anything one could write, demonstrates the wisdom of including the Establishment Clause in the First Amendment. States’ proposals for what became the Establishment Clause evidence the goal of accommodating competing religious beliefs. See, e. g., New York’s Resolutiomof Ratification reprinted in 2 Documentary History of the Constitution 190, 191 (1894) (“[N]o Religious Sect or Society ought to be favoured or established by Law in preference of others”).
State-sponsored universities in Louisiana already offer courses integrating religious studies into the curriculum. Approximately half of the state-sponsored universities offer one or more courses involving religion. As an example, Louisiana State University at Baton Rouge offers seven courses: Introduction to Religion, Old Testament, New Testament, Faith and Doubt, Jesus in History and Tradition, Eastern Religions, and Philosophy of Religion.
Of course, the difference in maturity between college-age and secondary students may affect the constitutional analysis of a particular public school policy. See Widmar v. Vincent, 454 U. S. 263, 274, n. 14 (1981). Nevertheless, many general teaching guides suggest that education as to the nature of various religious beliefs could be integrated into a secondary school curriculum in a manner consistent with the Constitution. See, e. g., C. Kniker, Teaching about Religion in Public Schools (1985); Religion in Elementary Social Studies Project, Final Report (Fla. State Univ. 1976); L. Karp, Teaching the Bible as Literature in Public Schools (1973).
For example, the political controversies in Northern Ireland, the Middle East, and India cannot be understood properly without reference to the underlying religious beliefs and the conflicts they tend to generate.
See N. Y. Times, May 10, 1981, section 2, p. 24, col. 3; N. McWhirter, 1986 Guiness Book of World Records 144 (the Bible is the world’s most widely distributed book).