In Science Translational Medicine, Eric VanEpps, Kevin Volpp and Scott Halpern suggest behaviorally informed interventions, or “nudges” that might be tested and implemented to improve patient recruitment and enrollment in randomized controlled trials (RCTs). Participant recruitment represents one of the largest costs of conducting RCTs, and barriers to recruitment can generate problems of selective enrollment and under-enrollment. The authors present a taxonomy of different approaches aimed at increasing clinical trial enrollment, based on behavioral economics principles. The proposed interventions address the patient barriers of imperfect information, desire for autonomy in making enrollment decisions, and resource constraints. For example, communicating that others have invested time and effort in designing RCTs can leverage individuals’ duties of reciprocity, while the “foot-in-the-door” technique first makes a small request and then follows with a larger request, thus using the patients’ desire for self-consistency to increase compliance. Future studies should test these nudges and note their effects, especially on vulnerable populations.