Book excerpt: Harry Potter fans contribute their immaterial and affective labor in multiple arenas: as peer-to-peer marketers via fan sites and social media; as participants in amateur fan festivals; or as activists for social change. Fans' participation in the Harry Potter universe has contributed to its success. This Element examines how fans' labor might continue to support the franchise for future readers. Starting with the context and theoretical frameworks that support a multidimensional analysis of the Harry Potter fan experience, this Element examines tensions between fans and Warner Bros., as fan participation tests the limits of corporate control.