This chapter examines the role of environmental factors and policies that influence health behaviors. It considers the effects of public policy-based solutions and social marketing approaches in changing behavior. Many social/health cognition models have been used to inform environment-based interventions. While the social norms-type approach has features of direct environmental effects on behavior, it is probable that this approach changes norms which in turn explain subsequent changes in behavior. There are two general types of social norms that guide behavior: descriptive and injunctive social norms. The chapter explores nudge theory and choice architecture as a research area that has examined how making changes to our environment might change our behavior. Some people might be uncomfortable with or even explicitly oppose nudges and choice architecture, especially if they are perceived as reducing personal autonomy and freedom, or if they are seen as ‘sneaky’ and being used outside of our awareness or consent.