Student self-efficacy, their confidence to successfully perform a task, is positively related to course performance. Students with high self-efficacy for a task are more motivated toward that task. Yet few studies have measured students' self-efficacy and motivation levels after exams are returned in introductory biology classes or studied how these levels relate to final course grades. To address these questions, we used structural equation modeling to examine how introductory biology students' (n = 123) self-efficacy and motivation scores at the beginning of the semester and after the first two course assessments related to their final course grades. Both self-efficacy and intrinsic goal orientation--motivated by a desire to learn or gain new skills--decreased after the first assessment grades were returned to the students. We found positive relationships between self-efficacy and motivation, and between self-efficacy and final course grades, across all timepoints. Motivation scores were not associated with final course grades, but the relationship between self-efficacy levels and final grades was significant and became stronger at each timepoint. These results suggest the importance of supporting self-efficacy development after early assessments, a time when students are particularly vulnerable to declines in confidence and motivation.