Two classroom studies tested whether mastery-approach goals and performance-approach goals nudge students to pursue different learning agendas. Each showed that mastery-approach goals promote an interest-based studying approach in which students allocate study time disproportionately to personally interesting material over duller material. Study 2 showed that this approach can jeopardize their academic achievement. Conversely, performance-approach goals promote a vigilant approach in which students seek cues about how to succeed and allocate study time toward material they believe is most important to their instructors. Study 1 showed that this approach encourages flexibility in how deeply they study material, and Study 2 showed that it facilitates achievement for students who are accurate in their beliefs about which material is instructionally important. These findings counter the assumption that performance-approach goals trigger a rigid reliance on superficial learning. They also therefore contribute to the broader discussion about when and why achievement goals affect achievement. (Contains 6 tables.)