IntroductionThe age of diagnosis is crucial for optimal health outcomes; however, some individuals with Autism Spectrum Disorder (ASD) may not be diagnosed until adulthood. Limited information is available about the lived experience of receiving a diagnosis during adulthood. Thus, we aimed to investigate stakeholders’ experiences about the ASD diagnosis during adulthood.MethodWe interviewed 18 individuals including 13 adults with ASD who had received a late diagnosis during adulthood and 5 parents of individuals with ASD from various Canadian provinces.ResultsUsing a thematic analysis, three main themes emerged: (a) noticing differences and similarities, (b) hindering elements to diagnosis, and (c) emotional response to diagnostic odyssey.ConclusionThis study adds to the literature about experiences of receiving ASD diagnosis in adulthood. Given the impact of diagnosis on individuals, it is important to minimize the barriers to ensure individuals who require ASD-related supports can access them in a timely and effective manner. This study highlights the importance of receiving an ASD diagnosis and facilitates positive health outcomes. The findings from the current study can be used to guide adult diagnostic processes and practices to help make ASD diagnosis more accessible.