This study investigated gender differences in science learning between two pedagogical approaches: traditional lecture and narrative case studies using personal response systems ("clickers"). Thirteen instructors of introductory biology classes at 12 different institutions across the USA and Canada used two types of pedagogy (Clicker Cases and traditional lecture) to teach eight topic areas. Three different sets of multiple regression analysis were conducted for three separate dependent variables: posttest score, change in score from posttest to final, and transfer score. Interactions between gender and pedagogical approach were found across the three analyses. Women either performed better with Clicker Cases, or about the same with either instructional method, but men performed markedly better with lectures in most topic areas. Our results suggest that men and women experience two pedagogical approaches--Clicker Cases and lectures--differently, and that Clicker Cases are more favorable for women than for men. (Contains 9 tables and 5 figures.)