This brief was developed as part of a portfolio of youth-focused projects on sexual risk avoidance and cessation sponsored by the U.S. Department of Health and Human Services. The brief presents two initial, complementary conceptual models—one for sexual risk avoidance and a second for sexual risk cessation—that aim to guide efforts to prevent youth risk behaviors and promote optimal health. The models identify a range of factors that research shows may influence youth decision making, sexual behavior, and related outcomes. These influencing factors occur at the environmental, interpersonal, or individual level, and many can be modified through intervention. To this end, the models may be used to guide and support efforts to develop and refine programs, tailor educational messages to youth, and empower parents and other adults to help youth avoid or cease sexual and non-sexual risk behaviors. In particular, the sexual risk cessation conceptual model is supporting the development of a sexual risk cessation program model and related supplemental curriculum module, intended to help sexually-experienced youth avoid sexual activity in the future.