Th is chapter introduces practice theory as a way of thinking about change agency. Th ough there are many ways that practice theory is implicated in change, I focus specifi cally on the relationship between designed artifacts and environmental sustainability. Th e emphasis on environmental sustainability is motivated by personal commitment and experience. Th e focus on practice theory and artifacts is motivated by both theoretical intuitions and empirical understandings. It is related to a theoretical intuition about the potential for conceptualizing change agency as distributed across interconnected assemblages of people, artifacts, and ideas. It is related to an understanding of the empirical context of sustainability as an area of social change in which there is a need for continuous updating of patterns of action. In the course of this chapter, I endeavor to develop and articulate these ideas and their connections.