This study investigated the relationship between childhood anxiety disorders, the valence and content of self-statements, and the impact of treatment on the internal dialogue. Participants (151 8- to 13-year-olds) included 71 youth with anxiety disorders and 80 control participants. Positive and negative self-statements and a states-of-mind (SOM) ratio were examined. Results indicated that the negative self-statements and SOM ratio (but not positive self-statements) of children with anxiety disorders significantly predicted anxiety. Results also indicated that negative (but not positive cognition) and SOM ratio predicted improvement in anxiety after treatment and mediated treatment gains. Results of analyses to explore the content specificity hypothesis were mixed. The impact of negative self-talk on children's anxious symptomatology and favorable treatment outcome is discussed.