In this lecture, Eugenie Birch draws heavily on history to illustrate the location, pace, trajectory, documentation and varied solutions of historic slum conditions in Western Europe and North America; tracking contemporary slum development in Latin America, Asia and Africa, and outlines the commonalities and differences with past experience. Birch places slum development in stages that correspond to the urbanization rates and peak growth of slums of the places in question, and discusses adaptations, their benefits and costs.