The Advanced Placement (AP) program has become a key step on the path to attending a selective college. In the University of California system, for example, more than 90 percent of applicants take AP or honors courses in high school (Geiser and Santelices 2006). However, the College Board estimates that nearly 300,000 high school students with the potential to succeed in an AP course graduate every year without ever taking one. Furthermore, high-achieving students from disadvantaged backgrounds are more likely than other high-achieving students to never take an AP class. Behavioral science researchers have shown that making small changes in the way information is presented can have a large impact on a person's decision to participate in a program. This issue brief examines how one such change--a personalized message added to a test score report--increased student participation in the AP program.