This study examines the interactions between people and the environment in the semi-arid Machakos District, Kenya over a period of 60 years. The study combines the findings of physical and social scientists from the Overseas Development Institute, London, and the University of Nairobi. It uses conventional data, oral history and photographic records dating back to 1937. As population growth is an inevitable consequence of the present age structure of many developing countries, the findings of the study will be beneficial to all those who are interested in agricultural change and rural resource management.