Human interference and environmental instability; addressing the environmental consequences of rapid urban growth in Bamenda, Cameroon describes the impacts of unplanned urban expansion and looks at both the underlying causes and the ecological and social implications. This expansion has placed great stress on forest, land and water ecosystems. Much of the city's rapid growth in population has been accommodated in informal settlements on steep slopes and flood plains, with little attempt being made to limit the risks of landslides, rapid erosion and flash floods. The paper ends with recommendations for protecting the remaining forest, for managing water resources and drainage systems and for ensuring that housing and other urban needs are met without jeopardizing the supporting ecosystems.