The focus of this chapter is on how MR-based neuroimaging techniques can be used to investigate the neurobiological basis of child psychiatric disorders. It is not a review of the literature, but rather discusses a number of examples to illustrate the utility of these techniques. First, we show how these techniques allow unprecedented access to the developing human brain as they can provide exquisitely accurate anatomical images as well as insight into the functional anatomy of the brain, without the use of ionizing radiation. Second, we explore how these techniques make it possible to explore human brain development in relation to the behavioral and cognitive developments that take place during childhood and adolescence, as well as their relevance to child psychiatry. Finally, we discuss neuroimaging studies of attention deficit disorder/hyperactivity disorder to illustrate how these techniques can be used to investigate the etiology of child psychiatric disorders.