BackgroundDrug abuse is a serious subject that can lead to social, economic, cultural and health problems. The routine approaches in treatment of drug abuse are either medication or non-medication methods. Non-medication approach is focused on mental and social health. Non-drug treatment requires appropriate tools.ObjectiveTo determine the validity, reliability, and structure of the Processes of Change Questionnaire.MethodsIn this cross-sectional study, which was conducted in 2016, three hundred sixty-two drug dependents in Sabzevar Substance Abuse Treatment Centers (Iran) were enrolled in the study. Samples were selected through the multi-stage sampling method. They completed the 40-item Processes of Change Questionnaire (drug version). In this study, Backward-Forward method, confirmatory factor analysis (CFA), test-retest, Cronbach’s alpha, content validity ratio (CVR) and content validity index (CVI) were used, using AMOS 5.0 and SPSS version 11.5.ResultsFindings of the CFA showed the questionnaire has a good fit. The fit index of the CFA was calculated as 0.75. Cronbach’s alpha was 0.93 for the whole questionnaire, and ranged from 0.51 to 0.88 for its different domains. Also, intraclass correlation coefficient (ICC) and content validity were satisfactory.ConclusionBased on the findings of this study, the processes of change 40-item questionnaire: drug version was a credible, reliable and valid tool to identify effective factors in the treatment drug abuse among the population of the Sabzevar, Iran.