Even as the U.S. population becomes steadily more diverse, minorities and women remain underrepresented in clinical trials to develop new drugs and medical devices. Although progress in increasing minority participation in clinical trials has occurred, participation rates do not fully represent the overall population of minorities in the United States. This underrepresentation threatens the health of both these populations and the general population, since greater minority representation could reveal factors that affect health in all populations. Federal legislation has sought to increase the representation of minorities and women in clinical trials, but legislation by itself has not been sufficient to overcome the many barriers to greater participation. Only much broader changes will bring about the meaningful participation of all population groups in the clinical research needed to improve health. To examine the barriers to participation in clinical trials and ways of overcoming those barriers, the National Academies of Sciences, Engineering, and Medicine held a workshop in April 2015. This publication summarizes the presentations and discussions from the workshop.