This study introduces the youth and caregiver versions of the Treatment Outcome Expectations Scale (TOES) and presents the results of comprehensive psychometric analyses in a large sample of clinically-referred youth (N = 291) ages 11-18 and their caregivers (N = 268). This study also examines whether expectations are predictive of early or overall treatment change as measured by changes in youth symptom severity rated by multiple respondents (youth, caregiver, and clinician). Additionally, the relationship between treatment outcome expectations and several background, pretreatment, and clinical variables is explored. Finally, this study investigates the correspondence in outcome expectations between dyads of youth and caregivers. Results demonstrate the TOES is a psychometrically sound measure for use in this population. Findings also indicate that while higher youth outcome expectations significantly relate to higher youth-rated internalizing symptom severity at baseline, they also relate to a faster rate of reduction in internalizing symptom severity. Additionally, caregiver age and youth gender were significant predictors of youth-rated outcome expectations. Results also demonstrate a small, positive correlation between youth and caregiver ratings of outcome expectations. Implications, future directions, and limitations of the study are discussed.