The current seven year WCEA/WASC/CAIS term of accreditation is through June 2021

WCEABishop García Diego High School is accredited by the Western Catholic Educational Association (WCEA). WCEA accredits Catholic elementary and secondary schools in nine western states (26 (arch) dioceses) and the US Territory of Guam. WCEA co-accredits and is in partnership with three Regional agencies (WASC, NAAS, NCA CASI) and two private agencies (CAIS and HAIS). WCEA began in 1957 in San Francisco and has a long and successful history of assisting school improvement through the accreditation process.

WASCBishop Garcia Diego High School is also accredited by the Western Association of Schools and Colleges. WASC is one of six regional accrediting associations in the United States. The Commission provides assistance to schools located in California, Hawaii, Guam, the Commonwealth of the Northern Marianas, American Samoa, the Federated States of Micronesia, the Republic of the Marshall Islands, and East Asia. The Accrediting Commission for Schools is composed of twenty-six representatives from educational organizations. The school has received six-year accreditation terms in 2008, 2002, 1996, 1990, 1984 and 1978.

CAISThe Board of Directors of the California Association of Independent Schools (CAIS) accepted Bishop García Diego High School into full membership in June 2010. CAIS membership includes more than 200 elementary, middle and secondary schools in California. The Association serves and strengthens its schools by setting standards of academic quality and ethical conduct, by providing for the professional growth of faculty, administrators, and trustees, and by promoting ethnic and socio-economic diversity.