Cal. Educ. Code § 223

This chapter shall not apply to the membership practices of the Young Men’s Christian Association, Young Women’s Christian Association, girl scouts, boy scouts, Camp Fire, or voluntary youth service organizations which are exempt from taxation under subdivision (a) of Section 501 of the federal Internal Revenue Code of 1954, whose membership has traditionally been limited to persons of one sex, and principally to persons of less than 19 years of age.