Impairment of adaptive functioning is a critical criterion in the diagnostic process for mental disorders, as well as clinicians’ preferred target when treating clients. At the same time, clinical research with youth overemphasizes mental health symptoms and undervalues measures of adaptive functioning. Moreover, there is a dearth of comprehensive assessments of functioning that are practical and validated for use with both youth and parents in clinical outpatient settings. The current study addresses these issues by examining the factor structure of both youth and parent versions of a measure of functional impairment. This study used an archival dataset of adolescents aged 11–19 years (87% Caucasian, 50% female) receiving services at a semi-rural community mental health clinic in Northwest Ohio. To determine the factor structure of functional impairment, exploratory and confirmatory factor analyses were conducted separately on youth and parent versions of the Ohio Scales Functioning Scale. Prior to analyses, the final sample of 1080 adolescents was randomly split in half in order to perform principal axis factoring on one half and confirmatory factor analysis on the other half. Overall, youth and parent Functioning Scales tapped into five domains encompassing youths’ school, social-emotional, recreation, self-care, and responsible behavior. However, there were slight differences in the item compositions of some domains, suggesting that youth and parents view certain behaviors as indicators of different aspects of functioning. Results support that youth adaptive functioning is a multi-dimensional construct, and the Ohio Scales may offer a more comprehensive assessment of functional impairment than other measures.