Assessing the needs of populations is a prerequisite for the planning and delivery of effective health services. This text presents the Life Cycle Framework as a means of organizing thought about this task from health district down to neighbourhood levels. The framework brings together in a coherent manner the diverse influences (e.g. biological, social, ethnic, environmental and geographical) on people's propensity for good health and their ability to avail themselves of services. It also identifies routinely available sources of information. The book is self-contained in that no prior knowledge of epidemiology is demanded of the reader. The intended readership includes a wide range of health professionals, managers and policy makers and those in other public sectors (e.g. local government) whose actions influence health. The Life Cycle Framework can also be used to assist in teaching social medicine to medical and nursing undergraduates and will be a valuable aid to trainees in public health medicine.