Alum Rock (/ˈæləm/) is a neighborhood and census-designated place in San Jose, California, in East San Jose. The CDP, which excludes all annexed areas, had a population of 15,536 at the 2010 census. It is home to Alum Rock Park, the oldest municipal park in California and one of the largest in the United States.
Formerly a separate town, much of the community is unincorporated surrounded by incorporated San Jose; neighborhoods between White Road and Capitol Avenue are part of a city/county agreement for annexation. James Lick High School, Mt. Pleasant High School, and William C. Overfelt High School (which are part of the East Side Union High School District), Joseph George Middle School, Ocala Middle School, and other schools in the Alum Rock Union School District serve the neighborhood. Near the center of the community is a small neighborhood commercial strip along Alum Rock Avenue at White Road.