Acalanes High School is a public secondary school located in Lafayette, California, United States, in the San Francisco Bay Area, within Contra Costa County. Acalanes was the first of four high schools established in the Acalanes Union High School District. It was built in 1940 on what was then a tomato field, using federal government funds with labor provided by the Works Project Administration, the largest and most ambitious New Deal agency introduced by the Roosevelt administration. Lafayette businessman M.H. Stanley suggested the name "Acalanes", the name of Rancho Acalanes, the Mexican grant from which all land title within the City of Lafayette derives. Rancho Acalanes itself seems to have been named by its Hispanic settlers after the local Native American Bay Miwok tribe called Saklan (Saclan), referred to by Spanish missionaries as Saclanes. The first graduating class of 1941 selected the school colors of blue and white. For the school sports mascot, they chose the Don (a Spanish honorary title).

Acalanes offers a diverse course selection and a number of AP and honors courses. Among the electives offered are sports medicine, digital design, auto mechanics, studio arts from beginning to AP, video production, journalism, drama, photography, Mandarin (Chinese), Spanish, French, chorus, band (four groups), and orchestra.

Acalanes High won the regional competition of the National Science Bowl at Lawrence Berkeley National Laboratory. However, the school has consistently lagged behind local high schools Campolindo and Miramonte in more comprehensive rankings based on AP scores and overall academic quality. For 2013, Campolindo High School was ranked 131st in the nation by U.S. News & World Report, Miramonte was ranked 173rd, while Acalanes was ranked 275th.

Football - 2023 Division 3-AA Champions

Girls basketball - 1999 Division 3 Champions

Girls volleyball - 2016 Division 3 Champions

Football - 2023 NCS IV Champions, 2024 NCS III Champions

Boys basketball - 2007 NCS III Champions

Baseball- 1997, 1998, 2007, 2011, 2012, 2013, 2016 NCS Champions

In 1939, Acalanes was the first school designed by Ernest Kump and became the prototype for what came to be called the "California School", consisting of a complex of rectangular single-story modern buildings in parallel rows separated by gardens, with no hallways. Its openness to the outdoors and ease of expansion were revolutionary at the time, and the format was widely copied.

The campus includes a track, several fields (an astroturf field, a grass field, and a baseball field), a pool, tennis courts, two gyms, weight room, two quads, and a performing arts center. Measure E bonds passed in 2008 provided for the complete renovation of the aquatic facilities, which was completed in the summer of 2011.

This article's list of alumni may not follow Wikipedia's verifiability policy. Please improve this article by removing names that do not have independent reliable sources showing they merit inclusion in this article AND are alumni, or by incorporating the relevant publications into the body of the article through appropriate citations. (October 2021)

• School website