Classen School of Advanced Studies (sometimes referred to simply as Classen SAS) is a public magnet school serving students in grades 6-12 in Oklahoma City, Oklahoma. The Oklahoma City Public Schools program participates in the IB Diploma Programme and offers fine arts courses.

Classen SAS has been ranked among the top 100 high schools in America by the Challenge Index, which is published annually in the Washington Post and Newsweek. Its current ranking is 66 , and had its highest rank on the list to date in 2006, when it was ranked 17th nationally .