Growth monitoring is widely accepted and strongly supported by health professionals, and is a standard component of community paediatric services throughout the world. We sought to evaluate research evidence of its impact. This requires definition, consideration of the setting, and discussion of the intended effects of this activity. In this review, we define growth monitoring as the regular recording of a child's weight, coupled with some specified remedial actions if the weight is abnormal in some way. Although the causes of growth faltering and the responses to it may be region specific, the process is the same, and we consider here growth monitoring in both the deprived and richer populations of the world.