This article reports a study of a newly created instrument designed specifically for the measurement of object relations concepts. The Comprehensive Object Relations Profile (CORP) is a semistructured projective test that asks the subject to respond to specific questions regarding interpersonal vignettes. Each question is designed to tap a particular dimension of object relationships. Three dimensions are measured: object constancy, object integration, and empathy. Validity was assessed by a comparison of three diagnostic groups: schizophrenics, borderlines, and neurotics. Reliability was measured by the interjudge method. The results indicated that the CORP significantly differentiated the three diagnostic groups in the expected direction and that the CORP is a highly reliable instrument. The implications of these results were drawn for both the usefulness of the CORP and the validity of object relations concepts.