This study compared two interventions to increase math self-efficacy among undergraduate students. Ninety-nine first-year undergraduate students participated in an intervention involving performance accomplishment or an intervention combining performance accomplishment and belief-perseverance techniques in which participants constructed a rationale for their future success in math/science university courses. As hypothesized, participants in the combined intervention immediately demonstrated higher math self-efficacy than did the Performance-Accomplishment only group; data convey that this effect was sustained at a 6-week follow-up. No differences were found between the groups in interest in technical careers, confidence in successfully completing math/ science courses, and willingness to enroll in math/science courses. Data analyses by gender indicated that male participants but not female participants in the combined intervention immediately demonstrated higher math self-efficacy than their counterparts. Findings suggest that self-persuasion activities may make an important contribution to enhancing math self-efficacy at least for men. Implications for women and future research are discussed. (Contains 2 tables.)