Book excerpt: "Prevalence of autism spectrum disorder (ASD) is estimated at one in 54 people (Maenner et al., 2020). Of people diagnosed with ASD in childhood, 85% continue to meet diagnostic criteria as adults (Billstedt et al., 2005). As with most neurodevelopmental disorders, ASD has historically been primarily studied as a disorder of childhood. However, this tide is changing. An estimated 50,000 adolescents with ASD age into adulthood every year (Shattuck et al., 2012). At this rate, we can expect upward of a half-million more adults with ASD every decade. This reality is inconsistent with the current research focus; only 2% of all ASD-related research focuses on adult outcomes (U.S. Department of Health and Human Services, 2017)"--