California Code, Education Code - EDC § 30

(a) English shall be the basic language of instruction in all schools.

(b) The governing board of a school district, or community college district, and any private school may determine when and under what circumstances instruction may be given bilingually.

(c) It is the policy of the state to ensure the mastery of English by all pupils in the schools, provided that bilingual instruction may be offered in those situations when that instruction is educationally advantageous to the pupils. Bilingual instruction is authorized to the extent that it does not interfere with the systematic, sequential, and regular instruction of all pupils in the English language.

(d) Pupils who are proficient in English and who, by successful completion of advanced courses in a world language or by other means, have become fluent in that language may be instructed in classes conducted in that world language.