The chapter discusses the behavioral changes and neurodevelopmental transformations that occur during adolescence, a period marked by the transition from childhood to adulthood. Key features of adolescent behavior, such as increased social interactions, risk-taking, and novelty-seeking, are common across various mammalian species and may aid in the acquisition of independence. These behaviors are influenced by changes in brain regions like the prefrontal cortex and limbic system, particularly the balance between mesocortical and mesolimbic dopamine systems. Pubertal increases in gonadal hormones are a hallmark of adolescence but do not fully explain behavioral changes. The chapter also explores the use of animal models to study adolescence, highlighting the challenges and validity of these models. It emphasizes that while adolescence is a period of significant behavioral and physiological changes, it is not uniquely human but is also observed in other species. The chapter concludes by discussing the prevalence and consequences of drug use during adolescence, noting that high levels of novelty-seeking are strong predictors of drug and alcohol use.The chapter discusses the behavioral changes and neurodevelopmental transformations that occur during adolescence, a period marked by the transition from childhood to adulthood. Key features of adolescent behavior, such as increased social interactions, risk-taking, and novelty-seeking, are common across various mammalian species and may aid in the acquisition of independence. These behaviors are influenced by changes in brain regions like the prefrontal cortex and limbic system, particularly the balance between mesocortical and mesolimbic dopamine systems. Pubertal increases in gonadal hormones are a hallmark of adolescence but do not fully explain behavioral changes. The chapter also explores the use of animal models to study adolescence, highlighting the challenges and validity of these models. It emphasizes that while adolescence is a period of significant behavioral and physiological changes, it is not uniquely human but is also observed in other species. The chapter concludes by discussing the prevalence and consequences of drug use during adolescence, noting that high levels of novelty-seeking are strong predictors of drug and alcohol use.