This study aimed to compare 2-year outcome among individuals with early-onset (EO; <18 years) versus adult-onset (AO) first-episode, non-affective psychosis. We compared clinical and treatment characteristics of 43 EO and 189 AO patients 2 years after their inclusion in a clinical epidemiologic population-based cohort study of first-episode psychosis. Outcome variables included symptom severity, remission status, drug abuse, treatment utilization, cognition and social functioning. At baseline, EO patients were more symptomatically compromised. However, these initial baseline differences were no longer significant at the 2-year follow-up. This study challenges the findings of a larger and older literature base consisting primarily of non-comparative studies concluding that teenage onset indicates a poor outcome. Our results indicate that adolescent-onset and adult-onset psychosis have similar prognostic trajectories, although both may predict a qualitatively different course from childhood-onset psychosis.