The last 40 years has seen a virtual revolution in both medical research and medical practice. Child psychiatry has been part of that revolution. The situation in the 1950s is briefly noted and seven examples are used to illustrate how causal research in the past has led to changes in clinical practice. The areas used as examples comprise: autism, hyperactivity/attention deficit syndromes, conduct disorders, depressive conditions, genetic research, organic brain dysfunction, and psychosocial risk processes. Prospects for the future with respect to the impact of research on clinical practice are discussed in relation to molecular genetics, environmental risks, cognitive and affective processing of experiences, links across the lifespan, and functional brain imaging. Attention is drawn to implications for training as well as for practice.