This report analyzes the relationship of Advanced Placement Program® (AP®) teacher practices and student performance on AP Biology and U.S. History exams. Using a national survey of AP teachers, the study developed four models for each subject with public school teachers only and both public and nonpublic school teachers, using two standards of success (scoring 3 or better and scoring 4 or better on the exams). Professional development and school and class context were statistically significant across all models; however, types of professional development differed. Resources were important for AP U.S. History teachers, while class size and schedule impacted AP Biology teachers. This indicates additional resources might enhance learning in AP U.S. History, while AP Biology teachers might be more effective with smaller, daily classes.