This chapter addresses how we develop, revisit, and negotiate norms around privacy when confronted with new technologies. The chapter first examines Nissenbaum’s (Washington Law Review 79(1):119–157, 2004) theory of privacy as contextual integrity, a framework that helps unpack how context-relevant norms for appropriateness and transmission can be challenged by new technologies. It then reviews how social norms develop as we build mental models of how a technology works during its diffusion process. The chapter concludes with suggestions for designers about approaches for thinking through implications when a design may challenge a preexisting social norm, or where there is no socially agreed upon norm. This includes careful reflection on who challenges to the current social norms may benefit and who they may hurt.