Mindfulness practices improve cognition, emotional balance, and well-being in clinical and non-clinical populations. The bulk of mindfulness research in higher education has focused on improving psychological and cognitive variables, leaving academic performance largely unexplored. We investigated the effects of a brief mindfulness intervention on quiz performance in two sections of an undergraduate upper-level human development class (N = 67). We used a between-group experimental design (waiting control group) and compared student quiz scores. Students assigned to practice mindfulness performed better on the first two quizzes than the control group. When the control group received the mindfulness intervention, there was no significant difference on quiz performance between the two groups. Mindfulness training did not impact state mindfulness or exam scores. Taken together, our results suggest that small doses of mindfulness training can briefly enhance students' knowledge retention of lecture content.