The authors evaluate impacts of web-based learning (WBL) for a geographic information system (GIS) course in which self-paced interactive learning modules replaced lectures to prepare students for GIS laboratory activities. They compare student laboratory, mid-term, final exam and overall scores before and after introduction of WBL, analyzing for gender differences in performance. Laboratory scores improved significantly for both males and females, though course grades did not change significantly overall for either group. Gender results show females performing better than males with either method. Most students were receptive to WBL. Future research is needed to understand what combination of graphics and text is most useful to students. (Contains 11 tables and 1 note.)