Introduction The Minnesota Multiphasic Personality Inventory-2-Restructured Form (MMPI-2-RF Ben-Porath & Tellegen, 2008/2011) has been applied to suicide risk assessment through derived proxy indices of perceived burdensomeness, thwarted belongingness, and the acquired capability for suicide (Anestis et al., 2018, Joiner, 2005). However, limited research has examined the clinical utility of these proxy indices outside the outpatient setting. This study examined the performance of these proxy indices in identifying past-month suicide ideation intensity and attempts upon admission to a psychiatric inpatient program and changes in suicidal ideation intensity at discharge. We expected these indices and their interaction would be associated with suicide ideation intensity and attempts at baseline and with a lack of significant improvement in suicide ideation intensity at discharge, including when controlling for MMPI-2-RF Suicide/Death Ideation (SUI) scale scores. Method Participants were 1007 patients in a private inpatient psychiatric hospital in the southwestern United States, 968 of whom completed study measures at admission and discharge. Participants were administered the C-SSRS and MMPI-2-RF upon admission, while the C-SSRS was administered again prior to discharge. A series of moderation analyses were conducted to examine the main and interaction effects of the MMPI-2-RF derived proxy indices on suicidal ideation intensity and suicide attempts at admission. Logistic regression analyses were conducted to examine whether MMPI-2-RF proxy index scores at admission were associated with changes in suicidal ideation intensity at discharge. Results Neither the proxy indices nor their interaction was associated with all study outcomes. The acquired capability for suicide proxy index and its interaction with other indices were not associated with suicide attempt status at admission. However, high thwarted belongingness proxy index scores were associated with greater suicidal ideation intensity at admission; high perceived burdensomeness proxy index scores were indicative of a lack of significant change in suicide ideation intensity at discharge. Conclusion These results indicate a need to further examine these proxy indices in high acuity samples.