California Code, Education Code - EDC § 51520

(a) During school hours, and within one hour before the time of opening and within one hour after the time of closing of school, pupils of the public school shall not be solicited on school premises by teachers or others to subscribe or contribute to the funds of, to become members of, or to work for, any organization not directly under the control of the school authorities, unless the organization is a nonpartisan, charitable organization organized for charitable purposes by an act of Congress or under the laws of the state, the purpose of the solicitation is nonpartisan and charitable, and the solicitation has been approved by the county board of education or by the governing board of the school district in which the school is located.

(b) A licensed dentist who provides voluntary dental health screening programs for pupils on school premises, shall not solicit a pupil, or the pupil's parent or guardian, or encourage, or advise treatment or consultation for the pupil by the licensed dentist, or any entity in which the licensed dentist has a financial interest, for any condition discovered in the course of the dental health screening. It is the intent of the Legislature that no licensed dentist use voluntary dental health screening programs for the generation of referrals or for financial benefit. The Legislature does not intend to deny or limit freedom of choice in the selection of an appropriate dental provider for treatment or consultation.

(c) A licensed optometrist who provides voluntary vision testing programs for pupils on school premises, shall not solicit a pupil, or the pupil's parent or guardian, or encourage, or advise treatment or consultation for the pupil by the licensed optometrist, or any entity in which the licensed optometrist has a financial interest, for any condition discovered in the course of the vision testing. It is the intent of the Legislature that no licensed optometrist use voluntary vision testing programs for the generation of referrals or for financial benefit. The Legislature does not intend to deny freedom of choice in the selection of an appropriate vision care provider for treatment or consultation.

(d) Nothing in this section shall be construed as prohibiting the solicitation of pupils of the public school on school premises by pupils of that school for any otherwise lawful purpose.