Known for creating feelings of euphoria, relaxation, as well as pain relief, marijuana has always been popular for both recreational and medical purposes. Marijuana is widely believed to be the most popular and accessible drug in the United States, with 48 percent of adults acknowledging that they tried it at least once. The legalization of recreational marijuana in Colorado and Washington, as well as the legalization of medicinal marijuana in 21 other states has created a paradigm shift that is impacting how marijuana is viewed within the fields of mental health, medicine, judicial and law enforcement, as well as business. This overview of marijuana use will explore the origins of the substance and what has led to its increase in popularity over the past decade. This course will also discuss how views on marijuana use has changed since its legalization in several states and how it is now viewed as Cannabis use disorder in the DSM-5. We will conclude with a review of appropriate treatment approaches for marijuana dependence.