The Outcome Questionnaire-45 (OQ) reliably quantifies level of psychological functioning and
change during treatment. The three subscales, however, are not well validated. Could alternative scales, based on personality dimensions or other psychological problems scales better explain patterns of response? In Study 1, the intended structure and four alternative models were compared using EFA and CFA in random thirds of a community clinic intake sample (N = 1,822). Oblique and bi-level models were compared. Preferred models were tested for stability in samples from later time points. In Study 2, the models were compared in a non-clinical sample (N = 589). Most bi-level models provided adequate fit per standards previously established for the Outcome Questionnaire-45. The seven-factor model provided better fit than any yet reported for this inventory.