The Schizophrenia Proneness ( SzP ) Scale: An MMPI-2 Measure of Schizophrenia Liability  P. Kevin Bolinskey Medical College of Virginia  Irving I. Gottesman University of Minnesota  David S. Nichols Pacific University We examined the psychometric properties and construct validity for a Minnesota Multiphasic Personality Inventory–2 Schizophrenia Proneness ( SzP ) scale (Bolinskey et al., 2001) and provided normative statistics. Premorbid participants were offspring of parents with schizophrenia- related illness (SRI), with comparison groups of offspring of parents with major affective disorders and offspring of normals. Postmorbid partici- pants were twins affected with SRI; their unaffected relatives served as a comparison group. Results suggest that an SzP T score of 65 or above is an effective indicator of personality processes associated with increased liability to developing SRI. © 2003 Wiley Periodicals, Inc. J Clin Psychol 59: 1031–1044, 2003. Keywords: endophenotype; construct validity; offspring of schizophrenics; twins The authors would like to thank L. Erlenmeyer-Kimling, of the New York State Psychiatric Institute and Columbia University, for allowing access to the NewYork High-Risk Project data; W. Grant Dahlstrom of the University of North Carolina at Chapel Hill for providing access to the MMPI-2 normative group data; and Alastair Cardno for providing diagnostic data for each of the Maudsley twins. We would also like to thank James N. Butcher, Robert P. Archer, and Randolph C. Arnau for their comments and suggestions on an earlier version of this report. This work was supported in part by NIMH Training Grant MH-20030 (P. Kevin Bolinskey). Correspondence concerning this article should be addressed to: P. Kevin Bolinskey, Virginia Institute of Psy- chiatric and Behavioral Genetics, 800 East Leigh Street, Suite 1, P.O. Box 980126, Medical College of Virginia, Richmond, VA 23298–0126; e-mail: pkbolinskey@vcu.edu. JOURNAL OF CLINICAL PSYCHOLOGY, Vol. 59(9), 1031–1044 (2003) © 2003 Wiley Periodicals, Inc. Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/jclp.10187