Cal. Labor Code § 3363.6

(a) Notwithstanding Sections 3351, 3352, and 3357, a person who performs voluntary service without pay for a private, nonprofit organization, as designated and authorized by the board of directors of the organization, shall, when the board of directors of the organization, in its sole discretion, so declares in writing and prior to the injury, be deemed an employee of the organization for purposes of this division while performing such service. (b) For purposes of this section, “voluntary service without pay” shall include the performance of services by a parent, without remuneration in cash, when rendered to a cooperative parent participation nursery school if such service is required as a condition of participation in the organization. (c) For purposes of this section, “voluntary service without pay” shall include the performance of services by a person who receives no remuneration other than meals, transportation, lodging, or reimbursement for incidental expenses.