Internalizing disorders of childhood and adolescence are common conditions, but until the past decade, had received little scientific scrutiny. This paper overviews the new knowledge that the past decade of research has given us. The early research began by adopting adult models of disorders, and adult-based modes of treatment. This met with moderate success, but the focus now is on testing whether these models are appropriate for younger clients. The good news is that, for adolescents at least, the adult models do seem to be appropriate. The bad news is that, even in well-resourced treatment trials, barely half of all cases remit. In very recent years, there has been a focus on generating developmentally appropriate models of childhood internalizing disorders, and correspondingly, an increasing interest in developing treatment approaches that are appropriate for young people and their families. The paper concludes with our thoughts on the most important questions for research in the next decade.