Cannabis is also known as marijuana, pot, dope, weed, grass, hemp, joint, and hashish. This psychoactive drug is the most widely used illegal substance in the world. The consumption of marijuana can lead to an array of physiological and psychological repercussions. Measures, questionnaires, and inventories can be administered to assess marijuana beliefs, behaviors, outcomes, and protective factors. This chapter focuses on reviewing the four major categories of marijuana self-report measures validated in the published literature: (a) cannabis beliefs (cravings, expectancies, and motivations), (b) cannabis usage (frequency and quantity), (c) cannabis outcomes (problems and consequences), and (d) protective factors against cannabis (confidence to resist temptations, self-efficacy to reduce use, protective behavioral strategies, and readiness to change). Several examples of popular validated measures from each of these categories are provided. For each cannabis measure, the development, factor structure, reliability, example items, and response options are described and discussed.