Background Practitioners need brief instruments to monitor outcomes in both treatment of drugs and alcohol addiction because they are useful to guide decision making in a short time.Objectives This study aims to develop a brief questionnaire, based on Client Evaluation of Self and Treatment, to evaluate the treatment effectiveness in drug and alcohol addiction treatment settings.Methods A cross-sectional study using a convenience sample (N = 608) recruited from Division for Intervention on Addictive Behaviours and Dependencies (DICAD – ARS North).Results The results show a new four-factor solution that accounted for 54.4% of the total variance and that provides the best fit to the data (c2/df = 1.72, CFI = .94, GFI = .91, RMSEA = .048 [.040-.057]; prmsea = .623). It also revealed a high internal consistency (a = .82). It was found a significant negative correlation (r = - .52, p < .01) between the final version of the instrument and a self report measure of psychopathology symptoms.Discussion This brief questionnaire, with good psychometric properties, can be useful to provide a viable and rapid feedback of treatment outcomes. Further studies should be performed to continue the evaluation of the reliability of this measure.