Autism Spectrum Disorders (ASD) are among the most common neurodevelopmental disorders, with an estimated prevalence of 1 in 110 children in the United States having an ASD. ASDs are typically diagnosed in early childhood, often at or before preschool age. The diagnosis is fundamentally behaviorally based (i.e., there is no specific genetic test or clinical/ laboratory procedure for diagnosis) and rests on documented core impairments related to social interaction, communication, as well as restricted and repetitive behavior. Diagnoses made by clinical providers, often pediatricians, behavioral providers, child neurologists, child psychiatrists, or child psychologists, are based on documented symptom patterns in these domains. Numerous screening and diagnostic tools are available to help document and measure symptoms of autism, with research investigations increasingly utilizing such measures in combination with clinical diagnoses in order to more accurately describe, measure, and analyze the heterogeneity in presentation associated with ASD. In addition to impairments in core symptom areas, many individuals with ASD also have impaired cognitive skills, atypical sensory behaviors, or other complex medical and psychiatric symptoms and conditions, such as seizure disorders, motor impairments, hyperactivity, anxiety, and self-injury/aggression. More than 55,000 individuals between the ages of 15 and 17 in the United States likely have an ASD. For some individuals, core symptoms of ASD (impairments in communication and social interaction and restricted/repetitive behaviors and interests) may improve with intervention and over time; however, some degree of impairment typically remains throughout the lifespan. As children transition to adolescence and young adulthood, developmentally appropriate interventions to ameliorate core deficits may continue, but the focus of treatment often shifts toward promoting adaptive behaviors that can facilitate and enhance independent functioning. The issue of the lack of services available to help young adults with ASD transition to greater independence has been noted by researchers for a number of years and is increasingly a topic in the lay media. The goal of this review is to examine the effects of available interventions on adolescents and young adults with ASD, focusing on the following outcomes: core symptoms of ASD; medical and mental health comorbidities; functional behaviors and independence; the transition to adulthood; and family outcomes. We have synthesized evidence in the published literature to address these Key Questions: Key Question 1: Among adolescents and young adults with ASD, what are the effects of available interventions on the core symptoms of ASD? Key Question 2: Among adolescents and young adults with ASD, what are the effects of available interventions on common medical and mental health comorbidities (e.g., epilepsy, sleep disorders, motor impairments, obesity, depression, anxiety, acute and episodic aggression, attention deficit hyperactivity disorder, etc.)? Key Question 3: Among adolescents and young adults with ASD, what are the effects of available interventions on functional behavior, attainment of goals toward independence, educational attainment, occupational/vocational attainment, life satisfaction, access to health and other services, legal outcomes, and social outcomes? Key Question 4: Among adolescents and young adults with ASD, what is the effectiveness of interventions designed to support the transitioning process, specifically to affect attainment of goals toward independence, educational attainment, occupational/vocational attainment, life satisfaction, access to health and other services, legal outcomes, and social outcomes? Key Question 5: Among adolescents and young adults with ASD, what harms are associated with available interventions? Key Question 6: What are the effects of interventions on family outcomes?