A great deal of research within science and engineering education revolves around academic success and retention of science and engineering students. It is well known that South Africa is experiencing, for various reasons, an acute shortage of engineers. Therefore, we think it is important to understand the factors that contribute to attrition rates in university students, and engineering students in particular. The theoretical framework for the present study draws on self-regulation theory, with particular reference to the role of self-efficacy and academic commitment. Participants comprised 127 engineering students in the second year of an augmented programme. They completed the "Academic Commitment Scale" and the "Materials Science Self-efficacy Scale." Statistical analysis included correlation and regression analysis to test the hypothesis that self-efficacy and academic commitment would predict the semester mark. Our results indicated that the self-efficacy and meaningfulness of materials science are significant predictors of investment, and that investment predicts the final semester mark. We discuss the results in terms of debates about throughput and retention for engineering students and also implications for teaching and learning.