OBJECTIVE The relationship between Tourette's syndrome (TS) and chronic tic disorder is of great clinical and scientific importance because of uncertainties in both prognosis and pharmacotherapeutic strategies. One approach to evaluating the relationship between TS and chronic tics is to examine whether they share similar neuropsychological and psychiatric correlates. METHODS Children with TS (n = 32) and children with chronic tics (n = 39) were ascertained from an unselected sample of the children referred for psychopharmacological treatment and examined using standardized diagnostic assessments and testing procedures. RESULTS Children with TS and those with chronic tics were similar to each other and different from controls in clinical correlates that included psychiatric comorbidity, as well as school, neuropsychological, and psychosocial impairments. Patients with TS also had higher rates of obsessive-compulsive disorder, oppositional defiant disorder, and simple phobia than did patients with chronic tic disorder. CONCLUSIONS These findings indicate that TS and chronic tic disorder are part of the same disease entity, with TS being a more severe form of tic disorder.