This chapter examines anxiety disorders in adolescents, specifically social anxiety disorder and generalized anxiety disorder, following the DSM-5-TR diagnostic criteria and emphasizing their relationship with substance use. It highlights that adolescents with social anxiety disorder face significant psychosocial challenges, marked by an heightened amygdala response to social threats, which contributes to avoidance behaviors and symptom persistence. Neurocognitive research identifies cognitive biases towards threatening social cues and altered brain activity patterns that exacerbate anxiety symptoms. In relation to generalized anxiety disorder, studies demonstrate hyperactivity in limbic responses, with structural brain changes affecting emotional regulation and cognitive control. The chapter underscores the prevalence of comorbidities, including depression and substance use disorders, and indicates that individuals may resort to psychoactive substances as a form of self-medication. It concludes by recommending comprehensive psychosocial interventions that integrate treatment approaches to improve outcomes for adolescents affected by these disorders and their associated substance use.