Risk taking and novelty seeking are hallmarks of typical adolescent behavior. Adolescents seek new experiences and higher levels of rewarding stimulation, and often engage in risky behaviors, without considering future outcomes or consequences. These behaviors can have adaptive benefits with regard to the development of independence and survival without parental protection, but also render the adolescent more vulnerable to harm. Indeed, the risk of injury or death is higher during the adolescent period than in childhood or adulthood, and the incidence of depression, anxiety, drug use and addiction, and eating disorders increases. Brain pathways that play a key role in emotional regulation and cognitive function undergo distinct maturational changes during this transition period. It is clear that adolescents think and act differently from adults, yet relatively little is known about the precise mechanisms underlying neural, behavioral, and cognitive events during this period. Increased investigation of these dynamic alterations, particularly in prefrontal and related corticolimbic circuitry, may aid this understanding. Moreover, the investigation of mammalian animal models of adolescence-such as those examining impulsivity, reward sensitivity, and decision making-may also provide new opportunities for addressing the problem of adolescent vulnerability.