The reliability and validity of the 12-item General Functioning (GF) subscale of the McMaster Family Assessment Device (FAD) is reported here. Psychometric properties of the FAD have been previously determined, but no independent assessment has been made of the GF subscale, which was used to measure family functioning in the Ontario Child Health Study (OCHS). Reliability was measured by Chronbach's alpha and split-half correlation. Validity was assessed by hypothesizing the relationships expected between the GF scores and other family variables included in the OCHS data set. The results indicate good reliability, and all hypotheses of validity were supported. The brevity and ease of administering the GF subscale recommend it for further use in survey research in which a global assessment of family functioning is required.