Clinical studies, studies that involve people, first use healthy people to test a drug’s safety and then use people with a disease or condition to prove that the drug works as intended. They are essential for bringing any new therapy to the public. Getting U.S. Food and Drug Administration approval for devices require rigorous studies, as well. Recruiting enough people to participate is often a long process, and for trials that may go on for a year or more, retaining people in the studies is often a challenge. People may get bored, find multiple study visits burdensome, have an adverse reaction to a drug being tested, move away, or drop out for a multitude of other reasons. If too many people discontinue the study, it will not have enough statistical ”power” to give a meaningful answer when the data are analyzed. Christine Hunter, BSN, RN, Research Director of the Parkinson’s Disease Center and Movement Disorders Clinic at Baylor College of Medicine in Houston, a Parkinson’s Foundation Center of Excellence, describes how her center finds people with Parkinson’s disease who may want to participate in trials, what factors drive retention in trials, and ways to facilitate retention.