Historically there is an acknowledged relationship between cities and state formation. This has been explored by scholars in relation to the formation of European nationstates hundreds of years ago. However we still know little about the role of cities in the transformation of states in the global South, and even less about the relationship between cities and state fragility. The Cities and Fragile States component of the Crisis States Research Centre’s work focuses on the pivotal and multiple roles of cities in processes of state transformation. We explore the dynamic tension between cities and states and how cities affect the ability of states to effectively deliver their core functions of security, growth and welfare.