Adolescence is a developmental period characterized by suboptimal decisions and actions, leading to increased risks of unintentional injuries, violence, substance abuse, unintended pregnancies, and sexually transmitted diseases. Traditional neurobiological and cognitive explanations have failed to account for the nonlinear changes in behavior observed during this period. This review presents a biologically plausible model of the neural mechanisms underlying these nonlinear changes. Recent human brain imaging and animal studies suggest that adolescents exhibit heightened responsiveness to incentives and socioemotional contexts, with impulse control still relatively immature. These findings indicate differential development of bottom-up limbic systems involved in incentive and emotional processing, compared to top-down control systems. This developmental pattern may be exacerbated in adolescents prone to emotional reactivity, increasing the likelihood of poor outcomes. The review discusses the role of individual differences in impulse control and risk-taking, and how these factors interact with emotional reactivity to influence adolescent behavior. The model reconciles contradictions about adolescent behavior, highlighting the importance of considering developmental trajectories and individual variability in understanding complex brain-behavior relationships.Adolescence is a developmental period characterized by suboptimal decisions and actions, leading to increased risks of unintentional injuries, violence, substance abuse, unintended pregnancies, and sexually transmitted diseases. Traditional neurobiological and cognitive explanations have failed to account for the nonlinear changes in behavior observed during this period. This review presents a biologically plausible model of the neural mechanisms underlying these nonlinear changes. Recent human brain imaging and animal studies suggest that adolescents exhibit heightened responsiveness to incentives and socioemotional contexts, with impulse control still relatively immature. These findings indicate differential development of bottom-up limbic systems involved in incentive and emotional processing, compared to top-down control systems. This developmental pattern may be exacerbated in adolescents prone to emotional reactivity, increasing the likelihood of poor outcomes. The review discusses the role of individual differences in impulse control and risk-taking, and how these factors interact with emotional reactivity to influence adolescent behavior. The model reconciles contradictions about adolescent behavior, highlighting the importance of considering developmental trajectories and individual variability in understanding complex brain-behavior relationships.