This report is about why and how city governments are taking a more responsible approach to the use of citizens’ data. It addresses some of the major flaws in how traditional smart city projects have approached data collection and use. It then provides a summary of policy roles available to local authorities to address these challenges. The report is based on case study research of a range of pioneering examples of city governments around the world that are trying to rethink how they collect, analyse and use data collected about people, and concludes with a set of eight lessons for how others can learn from these approaches.