This important book investigates a critical imperative. Urbanisation is an accelerating global process, and cities are now the defining organisational units of our time. Yet we have learned very little, beyond anecdote, about what effective city leadership is. This matters deeply. If the promise of global urbanisation is that it can alleviate poverty, reduce carbon emissions, advance productivity and increase resilience security, then whether that promise is ever realised, city by city, will depend in large part on how the cities are led, managed, championed and reformed.