45 C.F.R. § 86.14
(c) Voluntary youth service organizations. This part does not apply to the membership practices of voluntary youth service organizations which are exempt from taxation under section 501(a) of the Internal Revenue Code of 1954 and the membership of which has been traditionally limited to members of one sex and principally to persons of less than nineteen years of age.
(Secs. 901, 902, Education Amendments of 1972, 86 Stat. 373, 374; 20 U.S.C. 1681, 1682; sec. 3(a) of Pub. L. 93-568, 88 Stat. 1862 amending sec. 901)