Autism spectrum disorders (ASD) are a heterogeneous group of neurodevelopmental disorders that manifest in early childhood and persist throughout the lifespan; treatment should reflect the unique challenges for that individual at each developmental stage. In early childhood, treatment should focus on the acquisition of language, play skills, joint attention, and effective communication strategies through intensive behavioral and educational interventions, particularly Applied Behavioral Analysis (ABA). Middle childhood and adolescence presents a time for continued skills acquisition, including development of social skills, peer relationships, and maximizing supports for academic weaknesses. In older adolescence and young adulthood, developing vocational and adaptive living skills to maximize opportunities for independence becomes important. ASD are lifelong disorders, and treatment in adulthood includes ensuring opportunities for social, leisure, and vocational activities, maintaining physical health through diet and exercise, and support for transitions in caregiving as parents age. Throughout the lifespan, clinicians should remain mindful of medical complications that can affect behavior and may not be readily apparent in individuals with limited verbal abilities, including gastrointestinal problems such as reflux and constipation, seizures, and allergies. Current pharmacological interventions are primarily aimed at ameliorating the challenging emotional and behavioral symptoms that accompany ASD rather than the core symptoms of ASD themselves. However, substantial evidence-based research into most medications for ASD is lacking. Two atypical antipsychotics, risperidone and aripiprazole, have indication for the treatment of severe irritability in youths with ASD, though all other medication use in ASD is considered off-label. Behaviorally based therapies, including ABA and cognitive-behavioral therapy (CBT), may be helpful for symptoms of depression, anxiety, and impaired self-regulation. Clinicians should remain mindful that many families will seek out complementary and alternative medicine (CAM) approaches for their child, and appropriate guidance about the safety and efficacy of these interventions should be offered. Drug therapies that directly target the varied neurobiological underpinnings of ASD are an area of great interest for future research and treatment.