The API score measures how each school is performing academically compared to other schools. It's determined by results on standardized tests and the California High School exit exam.
Almost 40 percent of the state's elementary schools reached the target 800 score. Thirty percent of middle schools hit or surpassed the mark, but only 17.1 percent of high schools did.
State Superintendent of Public Instruction Jack O'Connell is concerned that the state's budget problems will hinder the improvement in student's test scores.
"I worry that these real gains in student achievement are in serious jeopardy because funding for our public school system is in serious danger. What kind of education will we be able to offer next year and the year after that with the kind of drastic and unprecedented cuts now under consideration?" O'Connell asked.
City News Service contributed to this report.