As art museums continue to engage youth audiences, a new program model has emerged: the drop-in art studio. Research suggests that intensive teen programs in museums are a powerful tool for youth development and audience building alike, but less is known about the impacts of drop-in teen programs. The purpose of this study was to describe how open studio programs impact youth participants' artistic self-efficacy beliefs. Questionnaires from 33 participants from three different art museum programs were analyzed, and interviews with 10 of the participants provided additional insights. Results suggest that participants perceived an increase in their self-efficacy beliefs in eight areas of artistic engagement: developing craft, engaging and persisting in their art work, envisioning further steps in their process, expressing feelings and ideas, observing the world around them, reflecting on their work and the work of others, stretching and exploring in the studio, and understanding the art community. Youth attributed the increase to specific aspects of the programs, including enactive attainment, modeling, verbal persuasion. These findings suggest that art museums may use artistic self-efficacy as an outcome for programs designed within this model.