Proposed by the EPA Section on Child and Adolescent Psychiatry and Neurodevelopmental Disorders Across the Lifespan (NDAL) -Autism spectrum disorder (ASD) is a neurodevelopmental disorder with a high prevalence, i.e. Centers for Disease Control and Prevention reported that 1 in every 54 (1.9%) 8-year-old children had been identified as having ASD in 2016. The symptoms of ASD – which are associated with significant impairment in family, social and/or educational, occupational, or other important areas of functioning - typically present in early childhood, and always persist into adulthood. Therefore proper assessment and comprehensive management of ASD is necessary across the lifespan. Moreover, individuals with ASD often present with comorbid disorders, i.e. altogether 70% of people with ASD have at least one co-occurring psychiatric disorder. The most common comorbidities next to ASD are mood disorders, anxiety disorders, and attention deficit hyperactivity disorder. All these can often lead to challenges in the assessment and management of ASD. The lectures of the symposium aim to help clinicians’ work in the field of ASD across the lifespan. The speakers are professionals from child to adult mental health services as well. The topics of the presentations include: 1) the introduction of a new semi-structured clinical interview designed to support healthcare practitioners in assessing ASD in children, young people, and adults (Susan Young). 2) the demonstration of challenges in the treatment of patients with ASD and comorbid ADHD through clinical cases (Judit Balazs). 3) Pharmacological treatment of adult Autism Spectrum Disorder (Josep Antoni Ramos-Quiroga), 4) Psychological management of adult Autism Spectrum Disorder (Kobus van Rensburg).