Self-efficacy in the mathematics/science domain is conceptualized as partially determining whether science, technology, engineering, and mathematics (STEM) students would persist toward reaching important milestones like graduating with a bachelor’s degree. The authors conducted a longitudinal study to examine if mathematics/science self-efficacy would significantly predict graduation status 4 to 8 years later after high school academic performance and mathematics aptitude were controlled in a university sample of introductory science students. Moreover, they looked at whether mathematics/science self-efficacy would significantly predict graduation status 4 to 8 years later after first semester grade point average (GPA) was controlled in addition to prior performance and aptitude. The sample consisted of 211 university students who graduated with a bachelor’s degree and 69 university students who did not graduate with a bachelor’s degree. The authors reported that mathematics/science self-efficacy significantly predicted graduation status 4 to 8 years later after controlling for prior performance and aptitude. The addition of mathematics/science self-efficacy improved the accuracy of identifying which participants dropped out before graduation by 4.4% in this sample. When first semester GPA was included in the control variables, the incremental contribution of mathematics/science self-efficacy to the prediction of retention status was null as expected. Findings are related to theory and prior research.