Middletown High School has its origins in 1919 with what was a one-building schoolhouse. Approximately 475 students attend Middletown High School from the town of Middletown and the surrounding communities of Cobb Mountain and Hidden Valley Lake. MHS is one of the five schools which comprise the Middletown Unified School District, whose geographic area encompasses communities clustered along Highways 29 and 175 in Lake County.