Many chronic illnesses and health conditions such as cardiovascular disease, certain cancers, and diabetes can be managed and prevented by behavioral means (World Health Organization, 2008). Epidemiological research has identified a “suite” of four key health behaviors associated with reduced risk of chronic illness: Taking sufficient physical activity, eating healthily, moderate-to-low consumption of alcohol, and refraining from smoking tobacco. Engaging in these behaviors has the impact of causing a nine-to 11-year delay in all-cause mortality (Ford, Zhao, Tsai, & Li, 2011). Furthermore, many other behaviors can promote better health outcomes such as handwashing for infection control, using sunscreen, and using barrier contraception. The development of large-scale initiatives to promote health behavior engagement at the population level or in key at-risk groups has, therefore, been identified as a priority by governments and health organiza tions (Michie & West, 2013; World Health Organization, 2008). Such initiatives have included media campaigns and advertisements, web-based programs, oneon-one consultations, and initiatives based in schools, the workplace, community organizations, and universities (e.g., Hagger et al., 2012; Hardcastle, Taylor, Bailey, & Castle, 2008). However, many interventions have not been optimally effective and fail to lead to expected changes in health-related behavior in the target population. Interventionists have therefore advocated evidence-based practice in behavioral intervention design and have highlighted the fields of health psychology and behavioral medicine as areas with considerable potential to inform the devel - opment of more effective interventions based on social psychological theory (Michie, Churchill, & West, 2011).