There has been an international turn to participatory democracy – enabling people to play an active role in decision-making that affects them – over the past three decades. Neighbourhood planning is a particularly striking example of this turn, with community groups given the power to write statutory planning policies for their areas. Its promoters portray it as a straightforward transfer of power from state to community which prioritises local knowledge and care for place. This book examines the complex realities behind that simple picture and the ways in which communities are simultaneously empowered and constrained by the process. It uses neighbourhood planning as a lens to explore how some things are made to matter in participatory practices and others are marginalised. It deploys a novel analysis, building on theories and approaches drawn from Science and Technology Studies, to understand how community voices achieve legitimacy and become effective or excluded through the selective enactment of different types of knowledge and care. It explores how this approach might be utilised in other sites of participatory democracy, including environmental justice movements, community organising in informal settlements, and participatory rural development. This new perspective opens possibilities for interventions in research and practice that could better deliver on the democratic claims made for participation, and provides lessons for a wide range of participatory practices that promise community empowerment by giving voice to local knowledge and concerns.