Cal. Const. art. XVI, § 5

Neither the Legislature, nor any county, city and county, township, school district, or other municipal corporation, shall ever make an appropriation, or pay from any public fund whatever, or grant anything to or in aid of any religious sect, church, creed, or sectarian purpose, or help to support or sustain any school, college, university, hospital, or other institution controlled by any religious creed, church, or sectarian denomination whatever; nor shall any grant or donation of personal property or real estate ever be made by the State, or any city, city and county, town, or other municipal corporation for any religious creed, church, or sectarian purpose whatever; provided, that nothing in this section shall prevent the Legislature granting aid pursuant to Section 3 of Article XVI.