The relationships between the three Modifier Indices (Disclosure X, Desirability Y, and Debasement Z) of the Millon Clinical Multiaxial Inventory-II (MCMI-II) and the validity and clinical scales of the Minnesota Multiphasic Personality Inventory-2 (MMPI-2) were explored. A sample of 125 psychiatric inpatients was administered both personality measures within 7 days of admission. The pattern of Pearson correlation coefficients and principal component factors was seen as generally supporting the validity of the three MCMI-II Modifier Indices. However, the Disclosure and Debasement Indices were highly intercorrelated and similar in their MMPI-2 associations. The Desirability Index functioned in a more unique manner and demonstrated both convergent and divergent relationships with MMPI-2 Validity and Clinical scales.