The AP Achievement Institute I (APAI I) is a four-day professional development program offered to teachers and administrators by EXCELerator™, a district reform program operated by the College Board. The APAI I program is designed to help teachers develop effective AP instructional strategies for a diverse student body and to help district, school, and curriculum leaders strengthen the district's infrastructure to support AP students and teachers. Teachers from a large urban school district on the West Coast participated in APAI I in the summer of 2009. The purpose of this project was to determine the impact of APAI I on student achievement on AP English language arts (ELA) and social studies exams. Students' AP Exam scores from the 2009 and 2010 administrations were examined for all participating teachers' students who took the AP English Language and Composition, English Literature and Composition, U.S. History, World History, European History, Comparative Government and Politics, U.S. Government and Politics, and Human Geography Exams. An appendix contains: APAI I Objectives (Summer 2009).