ABSTRACT Cannabis is the most commonly used illicit substance worldwide. Given the increasing trends of its use and the impression of its harmlessness, it is important to understand the user’s motivation to adjust prevention and intervention strategies. Thus, the present study sought to explore the psychometric properties of the motives to use cannabis among Portuguese cannabis users, describing the main motives for cannabis use and their associated factors. A sample of Portuguese adolescent and youth users (N = 212) were administered a sociodemographic questionnaire; a set of questions from the European School Survey Project on Alcohol and Other Drugs regarding lifetime, annual, monthly and weekly use; the Cannabis Abuse Screening Test; and the Comprehensive Marijuana Motives Questionnaire. The results allowed us to identify an adequate structure and reliability of the measure, with internal consistency ranging from .719 to .907. The main motives for using cannabis were to celebrate, enjoy and experiment, with some gender and age differences. Moderate correlations were found between cannabis use and sleep, altered perception and experimentation, explaining 46.5% of the variance in cannabis use. The results are discussed, and future directions are presented.