The Advanced Placement (AP) program is an educational program that permits high school students to take introductory college-level courses and receive college credit by passing a standardized end-of-course exam. Data were obtained from a statewide database of 2 high school graduating cohorts (N = 90,044). We used a series of propensity score analyses and marginal mean weighting through stratification to examine the impact of the AP program on students' academic achievement as measured by ACT scores. Results indicate that merely enrolling in an AP course produces very little benefit for students. Students who take and pass the AP exam, however, obtain higher ACT scores, even after controlling for a wide variety of academic, socioeconomic, and demographic variables. The authors conclude the article by discussing aspects of the AP program that remain unanswered.