There is a growing body of evidence that adolescents, and other children, are responsible for a significant proportion of sexual abuse against children. However, there are substantial differences in how this phenomenon is defined and conceptualized between and within sectors. This scoping review explored the current definitions of harmful sexual behaviors (HSB), and other similar terms, used across a range of stakeholder groups. In all, 141 papers were reviewed from both empirical and gray literature sources, including key policy and practice documents. Included papers needed to list a clear definition for the behavior of interest. There was disagreement and inconsistency across the included papers in their conceptualization of harmful, abusive, or problematic sexual behavior (PSB) in children and adolescents. Although the term HSB has been adopted as an umbrella term or continuum in many policy, practice, and research settings, there is a large variance in behaviors, treatment needs, etiology, and harms present across different types of sexual behavior. Relying solely on one term to describe a wide range of sexual behaviors in children and young people may limit the understanding of this issue and imply similarities between groups that are not present. We suggest that clearly defined subsets of HSB, such as sexual abuse, technology-assisted HSB, and PSB, may give more context to the behavior of concern and may be helpful in informing further research, prevention, and best practice approaches.