Brain imaging studies have demonstrated that psychotherapy alters brain structure and function. Learning and memory, both implicit and explicit, play central roles in this process through the creation of new genetic material that leads to increased synaptic efficiency through the creation of new neuronal connections. Although there is substantial evidence supporting some of the neurobiological effects of psychotherapy in adult patients, little exists on the impact of psychotherapy in children. Research has supported the enduring effects of early childhood trauma as represented by alterations in stress response, for example, which has important implications for early intervention through psychotherapy. Presently, the major questions facing the field of child and adolescent psychotherapy are identical to those in the study of adults. These can be reduced to four questions: what type of therapy, for what type of problem, in what type of child, and by what type of therapist. Areas needing further research are discussed.