This introduction proposes new directions for the social science of complementary and alternative medicine (CAM). It firstly reviews trends and gaps in the sociology of CAM, which has largely focussed on issues related to motivations for use, professionalisation struggles, and CAM’s relationship to biomedicine. CAM is more often treated as a signifier of social change than as a set of practices shaped by, and implicated in, epistemic and social transformations. By drawing on approaches from Science and Technology Studies (STS)—including actor-network theory and theories of boundary work, social worlds, co-production, and epistemic cultures—the chapter calls attention to CAM’s contingency, situatedness, materiality, and co-production within various spheres of governance and knowledge production. Such perspectives, it is argued, offer fruitful ways of comprehending what CAM is and how and why it is evolving.