Ralph J. DiClemente, PhD, is Charles Howard Candler Professor of Public Health and Pediatrics, Division of Infectious Diseases, Epidemiology, and Immunology and associate director, Emory Center for AIDS Research. Richard A. Crosby, PhD, is DDI Endowed Professor and chair, Department of Health Behavior, College of Public Health, University of Kentucky. Michelle C. Kegler, DrPH, MPH, is associate professor and deputy director, Emory Prevention Research Center, in the Department of Behavioral Sciences and Health Education in the Rollins School of Public Health, Emory University.