This paper describes how the Circumplex Model can be used for systematic assessment of a marital and family system. The three dimensions in the Circumplex are cohesion, change (adaptability) and communication. A variety of hypotheses have been derived and tested which validate the Circumplex Model. Clinical assessment and research can utilize the self-report scale, FACES III or the Clinical Rating Scale can be used to evaluate the family based on a clinical interview. A clinical evaluation of a problem family using FACES III and Clinical Rating Scale demonstrates the value of the tools for family assessment and treatment planning. The paper reflects the continuing attempt to further develop the Circumplex Model and more adequately bridge research, theory and practice.