More than half of the world’s children live in cities today. It is here that they learn, play, work and contribute in a multitude of ways to the making of places. Far from being just a ‘context’ for these young people’s lives, cities are significantly shaped by their activities and by the need to reflect their presence in the social organisation of life. Cities are of children and of youth in many ways. At the same time, what it means to be young is significantly shaped by the diverse ways in which cities and urban spaces are constructed and lived in the contemporary world. In order to understand how children, youth and the city relate, therefore, we need to consider both the manifold ways in which children and youth partake in the making of urban spaces, and the extent to which their experiences and practices correspond to wider social relations and the particular social and spatial construction of cities. In this book, we explore both sides of this relationship in order to show how and why young people’s urban lives play out differently in diverse cities around the world, while being connected through global power relations and age-related hierarchies. We aim to show both how children and youth contribute to the making of urban spaces and how the particular structures, textures and materialities of cities inform how they live their diverse lives.