Objective: We examined baseline demographic and clinical profiles of youths enrolled from 2001 to 2006 in the publicly funded multicenter, randomized controlled trial Treatment of Early-Onset Schizophrenia Spectrum Disorders. Method: Youths (8-19 years) with schizophrenia (SZ) and schizoaffective disorder were recruited at four academic sites. Diagnosis was made via structured and clinical interviews. Assessments of psychiatric symptoms and social and global functioning were included. Results: A total of 119 youths were enrolled. The mean age at illness onset was 11.1 plus or minus 3.5 years. Patients with SZ and schizoaffective disorder had similar ratings on the Positive and Negative Symptom Scale, Brief Psychiatric Rating Scale for Children, and Clinical Global Impression-Severity Scale. The overall level of functioning was similar in the two groups. A comparison to published reports of adults with SZ indicates that these youths may have more severe symptoms based on results of the Positive and Negative Symptom Scale. Conclusions: This is one of the largest samples of youths with SZ spectrum disorders studied to date and the largest assessment of youths with schizoaffective disorder. High rates of symptoms and general psychopathology were noted. There was a substantial degree of social and functional impairment. The symptom profiles are consistent with, but more severe than, those reported in the adult literature. (Contains 3 tables and 2 figures.)