The API was one of the main components of the Public Schools Accountability Act passed by the California State Legislature in 1999.
An API score was calculated for all students in a school as well as numerous API scores for each subgroup at the school (such as by race, English Learner Status, students with disabilities, and socioeconomically disadvantaged pupils).
Each rank ranged from 1 to 10, with a score of 10 meaning that the school's API fell into the top 10%.
Due to the API's heavy reliance on standardized testing (although some factors such as attendance and graduation rates were considered), many criticisms of standardized testing could also be leveled at the reliability and accuracy of API scores as an indicator of a school's level of "academic achievement."
In addition, the API was used to determine Adequate Yearly Progress as a part of the No Child Left Behind Act.