Research in higher education confirms the importance of self-efficacy in student persistence and success in college. The current study examined the role of self-efficacy in supporting academic and psychosocial adjustment in the critical first college year and the context of an academically-oriented first-year seminar (FYS). Students completed surveys at the beginning and end of the semester comprising Academic Self-Efficacy (ASE) and Psychological Well-Being (PWB) scales, and also provided background and demographic information. ASE increased over the semester, driven by improved confidence in research writing and class participation. Study/ time-management self-efficacy remained mostly unchanged. ASE was found to predict academic achievement and PWB, confirming our expectation that students' confidence in their academic ability would support positive academic and psychosocial outcomes. Results are discussed in terms of the value of efficacy-based pedagogical interventions as an intentional component of FYS delivery and design, and as a means of supporting student retention and success.