The purpose of this study was to determine if there were achievement gains in large classes with lectures alone versus with lectures and mentored groups. To measure achievement, mid-term to final-grade gains were compared between two sections (n=82 and n=99) of a undergraduate course in Digital Circuit Design that had lectures alone versus three sections (n=131, n=104, n=115) of the course that had lectures as well as mentored groups. In addition, the study surveyed students in one section in order to identify students' (n=115) satisfaction with the groups and mentors' (n=19) satisfaction with mentoring. Quantitative analysis using SPSS involved t-tests to identify significant differences. Results revealed statistically significant higher achievement for the three classes with lectures plus mentored groups versus the classes with lecture alone. Regarding satisfaction, 85% of students reported that they learned better in mentored groups. All mentors reported learning more as a mentor