The term ‘Third World city’ has been widely applied in urban and development geographies since the 1960s, and stems from a notion that there are distinct differences between cities in the developing and developed worlds. For the first time in history, the world is now predominantly urban, with most population growth occurring in towns and cities in the Global South. This chapter deconstructs the ‘Third World city’ concept before exploring the main schools of thought that have explored Third World cities since the 1950s: dualist interpretations of ‘Third World city’ structure; cities as theaters of accumulation and centers of diffusion; models of ‘Third World city’ structure; globalization and Third World cities; urban poverty, livelihoods, and sustainable cities; and spatial diversity within Third World cities. The latter section includes a discussion of prominent issues facing cities in the South, such as housing, livelihoods and the informal sector, gender and urban space, and cities for children. It concludes by arguing that the scale and extent of urban social inequalities in Third World cities suggest that they are not following exactly the same trajectories as Western cities.