The development of the Depression Proneness Rating Scale (DPRS) and three investigations into its reliability, validity, and factor structure are described. Subjects of all three studies were university undergraduates. The first study (n=100) found a stability coefficient of 0.82 for the DPRS over a test-retest (Time 1-Time 2) interval of 9 weeks. Further, Time-1 DPRS scores predicted Time-2 symptoms of depression independent of Time-1 symptoms. The second study (n=440) found the DPRS to be a better predictor of past depressive episodes than was the Beck Depression Inventory. The third study (n=1,101) found that all 13 items of the DPRS loaded 0.40 or greater on a single factor, and that this factor accounted for 44% of the total variance, more than eight times that of the next closest factor. Separate analyses showed identical factor structures for males and females. Overall, results provide substantial evidence for the DPRS as a valid, unidimensional measure of depression proneness. The DPRS and a 23-item list of references are included. (Author/TJH)