BACKGROUND: Tourette syndrome (TS) and chronic tic disorders (CTD) are stigmatizing disorders that may significantly impact self-esteem. Alternatively, comorbid psychiatric illnesses may affect self-esteem more than tics themselves. Extant research on self-esteem in TS/CTD is limited, has inconsistently examined the effect of comorbidities on self-esteem, and yields mixed findings. METHOD: This study aimed to clarify the roles of tics versus comorbid diagnoses on self-esteem in a large, carefully diagnosed sample of adults with TS/CTD (N=122) receiving 10weeks of Comprehensive Behavioral Intervention for Tics (CBIT) or Psychoeducation and Supportive Therapy (PST). RESULTS: Baseline self-esteem did not differ between adults with TS/CTD only and normative means, whereas self-esteem was significantly lower among adults with TS/CTD with a comorbid psychiatric illness. In a multiple regression testing the baseline association between tic severity, presence of comorbid psychiatric illness, and depression severity with self-esteem, comorbidity and depression severity were significantly associated with self-esteem, whereas tic severity was not. Finally, using a generalized linear model, we tested the effects of treatment assignment, comorbidity, and their interaction on changes in self-esteem across treatment, controlling for baseline depression severity. Results showed that for those with a comorbid illness, self-esteem improved significantly more with CBIT than with PST. CONCLUSIONS: Comorbid illnesses appear to affect self-esteem more so than tics among adults with TS/CTD. Therapeutic attention should be paid to treating comorbid diagnoses alongside tics when treating TS/CTD.