This study investigated the effectiveness of the Child and Adolescent Functional Assessment Scale (CAFAS) for assessing the functioning of youth with mental disorders. The CAFAS is a multidimensional tool used to record the extent to which a youth's mental health disorder is disruptive of functioning in each of five psycho-social areas: role performance, thinking, behavior towards others, moods, and substance abuse. The CAFAS was used to collect admission data on 213 patients (ages 3-20) at a residential center and discharge scores for 102 patients. Initial results using the CAFAS were encouraging; patients typically had a total admission CAFAS score of over 80, indicating a need for intensive services. Patients admitted to the center were most likely to show disturbances in function for role performance, behavior toward others, or moods. Average scores showed a statistically significant change at discharge, indicating patients were improving their levels of functioning during treatment. A group of 28 patients with lengths-of-stay under 31 days also showed statistically significant changes in their scores after treatment, suggesting that the CAFAS can detect changes in levels of functioning independent of length-of-stay. (CR)