Child and adolescent therapy has progressed considerably, as reflected in the number of controlled studies, their methodological quality, and identification of evidence-based treatments. Treatments with strong evidence in their behalf are used for several clinical problems. Despite the progress, several key areas have been neglected in research and this has greatly limited what we know about treatment. Prominent among these areas of neglect is research on the mechanisms of change, the moderators of treatment outcome, and the generality of research findings to the conditions of clinical practice. This article highlights progress, characteristics, and limitations of current therapy research. In addition, a research plan is offered to advance research by (a) understanding the mechanisms or processes through which therapeutic change occurs, (b) drawing on developmental psychopathology research to inform treatment, (c) expanding the range of questions that guide treatment research and the range of outcome domains on which treatment conclusions are based, and (d) monitoring progress to ensure that critical questions about treatment are addressed.