The use of psychological testing in child custody assessments has become more common and important as psychologists are increasingly used as expert witnesses in contested child custody and visitation cases. Currently, the MMPI-2 is the most commonly used psychological test in child custody cases, but there is no research indicating which version of the measure (K-corrected, non-K-corrected, or the RC scales) provides the most accurate picture of the custody litigant in terms of substantial correlations with external variables. This study represents the first examination of the convergent, discriminant, and incremental validity of the MMPI-2 K-corrected Basic Clinical Scales, the MMPI-2 non-K-corrected Basic Clinical Scales, and the RC scales in a sample of (n = 196) custody litigants from the Mid-Atlantic region of the United States. Results indicated that all three sets of scales showed some evidence of convergent validity and discriminant validity with external criteria, with gender differences shown in correlate patterns. Additionally, results indicated that none of the three versions demonstrated incremental validity relative to the other versions. There were several limitations of the study including the use of dichotomous, self-report external correlate variables, the simultaneous collection of both predictor and outcome variables, and potentially limited generalizability of the data.