The validity, reliability, and curvilinearity of the Clinical Rating Scale (CRS) from the Circumplex Model were evaluated and the ability of the scale to discriminate between proble/clinical families and nonclinical families was tested on family cohesion, family adaptability, and family communication. Two groups of problem families were compared with two control groups. The study tested the main curvilinear hypothesis of the Circumplex Model that nonclinical families will have more Balanced system types than problem/clinical families. Conversely, problem/clinical families will have more Extreme system types than nonclinical families. Using the CRS, this hypothesis was strongly supported. Family satisfaction was used as a measure to investigate group differences further. As hypothesized, the two control groups had high levels of satisfaction, and the two problem family groups had significantly lower levels of family satisfaction. Overall, the CRS discriminated well between problem families who had more Extreme types on cohesion and adaptability and lower on communication and satisfaction than control families. Investigating different family structures (single‐parent, blended, and traditional two‐parent families) confirmed these findings. The study provided strong support for the curvilinear hypothesis that problem families are more frequently Extreme on both ends of the family cohesion and adaptability dimensions. It also revealed that the CRS has excellent validity and reliability.