Epistemic beliefs are one's assumptions about knowledge and knowing. Given the research in educational psychology that established epistemic beliefs as reliable predictors of student success, we devised a pedagogical intervention to improve students' epistemic beliefs. In this study, we examined the effectiveness of the reflective writing task as a means of changing how students think about what is known. Students from two upper-level psychology classes (Cognitive and Research Methods) took a general epistemic belief survey by rating their agreements with 38 items at three different times in a semester (first-day, pre-reflective-writing task, and post-reflective-writing task). Day 1 responses were utilized to validate the survey items using principal component analysis--three variables (Knowledge Construction and Modification-KCM, Structure of Knowledge-KST, and Meaning of Successful Students-SS) emerged. The intervention successfully improved students' beliefs specific to Structure of Knowledge-KST and Meaning of Successful Students-SS, beliefs that predict student learning. This study suggests that even short interventions have the potential to influence students' beliefs about knowledge, which have been shown to have demonstrable effects on their academic success.