As student-centered approaches to teaching and learning are more widely applied, researchers must assess the outcomes of these interventions across a range of courses and institutions. As an example of such assessment, this study examined the impact of inquiry-based learning (IBL) in college mathematics on undergraduates' subsequent grades and course selection at two institutions. Insight is gained upon disaggregating results by course type (IBL vs. non-IBL), by gender, and by prior mathematics achievement level. In particular, the impact of IBL on previously low-achieving students' grades is sizable and persistent. The authors offer some methodological advice to guide future such studies.