High Quality Content by WIKIPEDIA articles! Castilleja School is an independent school for 415 girls in grades six through twelve, located in Palo Alto, California. Castilleja is the only non-sectarian all-girls middle and high school in the San Francisco Bay Area. Castilleja is accredited by the Western Association of Schools and Colleges and is a member of the National Association of Independent Schools, the National Coalition of Girls Schools, and the College Board. In late 2007, the Wall Street Journal identified Castilleja School as one of the world`s top 50 schools for its success in preparing students to enter top American universities.