This study evaluated the capacity of the Willingness Scale (WS) to predict changes in depression over the course of a brief inpatient admission. Two cohorts (N = 160) of adult inpatients completed the Willingness Scale along with a measure of depression following admission. Depression severity was assessed approximately 4 days later, prior to discharge. Data were evaluated using structural equation modeling. Higher WS scores predicted greater reductions in depression in both cohorts, and the magnitude of this effect was large. The fits of the models were outstanding, with no significant differences in any parameter estimates across the two cohorts. The WS predicts changes in depression, even within a brief inpatient admission where the treatment is predominantly biological. These results replicate results of previous studies in outpatient populations where CBT was the primary treatment and suggest motivational factors may play an important role in causation and recovery from depression.