We outline an implicit cognition, verbal, and nonverbal assessment approach that is feasible for a range of interventions in health behavior and addiction. This approach provides a way to assess whether interventions have an influence on the relatively spontaneous memories, thoughts, and evaluations that may mediate or precipitate health-related behaviors (alcohol, tobacco, and other drug use; HIV risk behavior; diet, exercise, and violent acts). We focus on feasible assessment applications in relapse prevention, and briefly provide several examples of assessments also relevant to secondary prevention and media interventions, with a focus on addictive and HIV risk behaviors. The assessment examples range from well-investigated tests with grounding in basic research to assessments that have much promise for application but are yet to be thoroughly evaluated. The approach suggests that implicit cognition assessments may help practitioners uncover and address plausible cognitive mediation effects that are unlikely to be currently assessed.