Liberal views on cannabis use are widespread in many Western countries, but prohibitionism remains strong in Sweden. According to Swedish drug policy, comprehensive prevention and treatment interventions are necessary because young people are considered particularly vulnerable to cannabis-related harm. In this article, we examine how staff at Swedish outpatient treatment centers for young substance users (called “MiniMaria”) use different logics when legitimizing their work in youth treatment. We also analyze how this legitimizing process contributes to both justifying solutions and constituting the cannabis “problem” that MiniMaria centers are established to handle. This will shed light on what “drug reality” the staff make up through their articulations. Eighteen interviews with social workers from six MiniMaria centers in the Stockholm region were analyzed. To illustrate how staff made sense of their work, we used the concepts of “problem representation”, “legitimation”, and “logics”. We identified four logics: A scientific and a structural logic linked to knowledge claims, policy goals, and organizational setting, and a professional and a procedural logic linked to work experience, client interaction, and therapeutic methods. Participants used logics to emphasize that the character of the cannabis problem demands wide-ranging interventions and to explain how they made youth cannabis users realize they need treatment. The structural logic of drug prohibitionism was only mentioned as a last resort when other logics were not applicable, for example, when a young person refused to engage in treatment and quit using cannabis. The strategic use of logics provided MiniMaria with a moral legitimacy that represented youth cannabis use as a high-profile problem and young people as in need of protection and control. This legitimizes prevention of youth cannabis use in a national setting where cannabis prevalence and harm remains relatively low.