California Science and Engineering Fair

The California Science and Engineering Fair (or CSEF), previously known as the California State Science Fair, is a science fair held annually in Los Angeles, California. It serves as the final science fair of the academic year and is a feeder competition to the International Science and Engineering Fair (ISEF) and the Thermo Fisher Junior Innovators Challenge (TFJIC). First established in 1952, CSEF was designated the state's official science fair in 1990 and ran its 74th fair in 2025.

The fair is fed by 28 regional science fairs, each of which is allocated a number of projects based on prior history of producing winning entries. The allocation in 2009 was 908 projects, an average of 24.7 projects per million population.

Awards are given in several categories at both junior (grades 6–8) and senior (grades 8–12) levels. The awards are posted shortly after the fair ends each spring. At the 2009 fair the major awards include the Patricia Beckman Project of the Year Award—David Zarrin of Redwood Middle School, Saratoga won the Junior Division ($5,000 award) and Anna K. Simpson of Patrick Henry Senior High School, San Diego won the Senior Division ($10,000). There are also many special awards sponsored by various organizations, some with cash prizes. An example of the special awards presented include the UCLA Brain Research Institute Award (given to Senior and Junior Divisions) that was recently awarded to Luke T. Anderson of De La Salle High School.

No fair was held in 2020 as officials cited the COVID-19 pandemic as grounds for cancellation. The 69th was deferred to 2021.