A postexam review activity was implemented in an introductory biology course to help students learn from their mistakes and strengthen reasoning and self-regulatory skills. The goal of this study was to design and test a strategy to measure the effectiveness of the postexam review using student performance and attitudinal measures. We evaluated student work for correctness, completeness, and quality of the explanations associated with corrections, and we examined the relationship between quality of responses and performance on course examinations. We investigated the number and variety of strategies and behaviors that students used when preparing for exams and examined student perceptions related to the postexam review as a learning activity. Our results illustrate the potential value of this activity for students and instructors but reveal difficulties that students encounter and inconsistencies between performance and perception. Our findings prompted us to increase the amount of guidance and feedback we offer students and to incorporate additional exercises that promote the development of self-regulatory skills.