Psychological models of pediatric obsessive-compulsive disorder (OCD) place a heavy emphasis on harm avoidance as a maintaining factor and target for treatment. Incompleteness and disgust may also play a role in pediatric OCD but remain under studied. Youth with OCD (n=100), anxiety disorders (n=96), and no psychiatric disorder (n=25) completed self-report measures of trait-level incompleteness, harm avoidance, and disgust and current symptoms of OCD, anxiety, and depression. Group differences and associations between emotions, symptoms, and pre- to post-treatment change in overall OCD severity were examined. Youth with OCD and anxiety disorders scored higher on harm avoidance and disgust than youth with no psychiatric disorder. Youth with OCD scored higher on incompleteness than youth with anxiety disorders and youth with no psychiatric disorder. Harm avoidance showed unique associations to self-reported symptoms of OCD, anxiety, and depression while incompleteness was uniquely related to OCD and disgust to anxiety. Within the OCD sample, incompleteness and harm avoidance were differentially related to the major OCD symptom dimensions, and change in incompleteness was uniquely related to pre- to post-treatment change in OCD severity. Trait-level incompleteness appears to play a central role in pediatric OCD and studies investigating its direct involvement in symptoms and associations with treatment outcome are needed. The role of disgust in relation to pediatric OCD remains unclear.