Increasing the number of students choosing a STEM (science, technology, engineering, and mathematics) career is a national educational priority. One way thought to increase interest in STEM is with advanced STEM courses in high school, especially Advanced Placement (AP) courses. Using data from 15,847 college undergraduates, we investigated the relationship between participation in AP mathematics courses (AP Calculus and AP Statistics) and student career interest in STEM. After controlling for covariates, the strongest effect (d = 0.13) showed that students who took AP Calculus had a modestly higher career interest in engineering and mathematics/computer science. However, the relationship between most AP mathematics courses and most STEM career outcomes was negligible. Most differences in outcomes between AP and non-AP students are likely due to preexisting differences between the two groups.