Clinical research requires the measurement of complex variables in a manner that is as simple as possible while still being precise. This paper presents a clinical rating scale that was developed as a global measure of the quality of couples' relationships. These couples participated in a study that investigated asthma onset in children at genetic risk for developing this illness. The ratings of marital quality at the prenatal point were significantly related to the number of behavior problems the children were reported to have at 2 years of age. The use of the scale is outlined, together with descriptive data for this group. Reliability data and evidence for predictive and construct validity are presented.