The Del Mar Union School District (DMUSD) is a public school district based in Del Mar in San Diego County, California. The district was founded in 1906.^[3] For many years, the district was small, serving approximately 1,000 students in the City of Del Mar. However, in the 1990s, the district's boundaries were expanded to include the newly developed Carmel Valley subdivision in the City of San Diego. Today, approximately 4,000 children attend the district's eight schools.

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The district is well regarded for its high standardized test scores. In 2006, the district scored 939 on the Academic Performance Index, higher than any other district in San Diego County. This top-ranking was repeated in 2007. Individually, Sage Canyon School has posted the highest Base APIs scores in the County from 2004 to 2008.

The district consists of eight K-6 schools:

• Ashley Falls School
• Carmel Del Mar School
• Del Mar Heights School
• Del Mar Hills Academy
• Ocean Air School
• Pacific Sky School
• Sycamore Ridge Elementary School
• Torrey Hills School

Together with the schools in the Solana Beach School District, the Del Mar Union elementary schools generally feed into Carmel Valley Middle School and onto either Torrey Pines High School or Canyon Crest Academy, all part of the San Dieguito Union High School District.^{[citation needed]}