With an over 20-fold increase in population between 1963 and today, Lagos has expanded significantly both within and outside its city administrative boundaries. Some paradoxes are identified using mixed methodologies from a qualitative research design. Lagos’s northwards expansion has exerted several externalities on a neighbouring state. Expansion within Lagos, on its coastal south-eastern axis, is defined by real estate activities of a different nature. In both cases, new settlements have emerged with differing social and economic characteristics that have far-reaching impact for housing accessibility and affordability. These differences are explored by establishing pull-factors responsible for attracting specific income groups to each axis, the impact of government action (and inaction), and the implications of these for city growth and management. Formal mechanisms of planning lead to a proliferation of higher end real estate development. This has created unequal access to land and housing for lower income families. The subsequent exclusion of lower income families from planned areas represents a failure of the market system. Lagos presents compelling complexities of the management of urban expansion that spread beyond administrative boundaries, as well as the influence of planning to achieve economic development.