Life history approaches to the study of inequalities in health provide evidence that the biological and the social beginnings of life carry important aspects of the child's potential for adult health. Biological programming may set the operational parameters for certain organs and processes. Social factors in childhood influence the processes of biological development, and are the beginnings of socially determined pathways to health in adult life. Life history studies of health are beginning to show the important factors associated with the development of these pathways, and the life stages at which intervention to reduce adult health inequalities may be most effective.