Background and Objective: The motivation for marijuana use can be a major predictor in actual marijuana use. This study focused on assessing the psychometric properties of the Marijuana Motives Measure (MMM) among young adult marijuana users in Iran. Materials and Methods: This study was carried out in 2016, involving 166 young adults from Isfahan and Kermanshah, Iran. The study assessed the cultural acceptance, face validity, content validity, construct validity, exploratory factor analysis, and internal consistency of the MMM. Results: The average age of the respondents was 20.51 years (95% CI: 20.19, 20.82), ranging from 17 to 25 years. Face validity was assessed and approved by a panel of experts. Additionally, content validity was verified using the results derived from the Lawshe table. Five factors were identified based on Eigenvalues of ≥ 1.00 and factor loadings of ≥ 0.40. The variances and the factor load ranges of the MMM factors were respectively as follows: “conformity”: 24.860% and 0.635-0.894; “expansion”: 16.481 and 0.618-0.823; “coping”: 10.499% and 0.686-0.818; “social”: 8.900% and 0.676-0.775; and “enhancement”: 5.818% and 0.707-0.759. The questionnaire had a Cronbach's alpha of 0.833, with its components showing Cronbach's alpha values ranging from 0.717 to 0.850. This indicates satisfactory levels of internal consistency for each component. Conclusion: Our findings suggested that the Persian version of MMM is a psychometrically sound questionnaire for measuring marijuana motivation use among Iranian young adults.

Introduction: Regarding the prevalence of substance abuse among students, this study aimed to validate the Substance Use Motives Measure (SUMM) in this group. Materials and Methods: The statistical population consisted of all high school students in Kerman city, Iran in 2022. We selected students using the multistage cluster sampling method. Out of 1045 students, 977 answered to the Substance Use Motives Measure (SUMM) and the Farjad's Addiction Tendency Scale. We used content validity indices, Pearson correlation coefficient, exploratory and confirmatory factor analysis, Cronbach's alpha, Guttman coefficient, and split-half coefficient. The data were analyzed through SPSS-22 and LISREL 8. 8 software. Results: The SUMM had high content and concurrent validity. The results of structural validity showed that the eight-factor model of the SUMM had appropriate fit indices, and this model explained 68. 84 percent of the total variance. The results of the internal reliability of the SUMM showed that Cronbach's alpha and split-half coefficients for the whole scale and its eight factors were in the range of 0. 81 to 0. 95. Conclusion: Based on the findings, the Substance Use Motives Measure (SUMM) has appropriate validity and reliability and can be used to assess addiction motives in students.