Financial literacy is an important life skill, yet the impact of financial education has often been found to be modest. We conducted a field experiment to assess the effectiveness of a postinstruction intervention using a smartphone app that incorporated cognitive science principles aimed at improving learning. College students who completed a required credit review workshop during their sophomore year used the smartphone app in one of three practice conditions: control (no practice), massed, or spaced retrieval practice with elaborative feedback. On a final assessment about 5 months later, students who engaged in spaced retrieval practice were superior to those in the control and massed practice conditions in terms of knowledge. Given the ubiquity of smartphones today, the results highlight the potential of harnessing easily accessible technology as learning tools to augment the retention and transfer of knowledge.