Support for the efficacy of cognitive—behavioural therapy (CBT) for anxious youth has accumulated. Significant treatment effects are observed and maintained over the long term for the majority of children receiving individual, family or group-based treatments. Nevertheless, all children do not improve. In fact, there is evidence to suggest that a significant percentage of children continue to experience anxiety following treatment and will seek additional treatment for their anxiety. This article will review the substantial evidence for CBT, the current information available on predictors of outcome and mechanisms of change. The article will also discuss the need for adequately powered randomised clinical trials that continue to refine and evaluate treatments for anxious children in an effort to improve outcomes for those children whose needs are not being met by our current treatments.