This exploratory study examined and compared overall trends in growth and student achievement of the Advanced Placement (AP) program. Using data from the past two decades, analyses indicated there has been steady and extensive growth of AP participation, particularly among underclassmen and some minority groups. However, overall achievement, as measured by pass rates, has declined somewhat over the last 20 years with the proportion of students earning the lowest AP score of a 1 increasing twofold. Possible underpinning causes discussed include limited course choices for high ability students, in-class incentive recruitment practices, and changing ethos about AP.