This professional presentation provides an overview of the historical development of ADHD and ASD diagnoses across DSM editions, highlights shared and distinct features of both conditions, and describes how the recent DSM replaced the exclusion criterion with an option for dual diagnosis. In the decade since that change, some adults diagnosed with ADHD have begun exploring whether their neurodivergent presentation may be better characterized as AuDHD. More specifically, this first section offers a historical and diagnostic overview of ADHD and autism, and acknowledges neurodivergence as an identity. It examines the role of differential diagnosis and emphasizes the importance of neuro-affirming, trauma-informed neuropsychological and biopsychosocial assessment that incorporates gender, age, and intersectionality into clinical formulation. The second section focuses on supporting clients with treatment approaches and referrals tailored to AuDHD symptom presentations, drawing on a multimodal approach and emphasizing interdisciplinary collaboration among mental health clinicians, medical providers, educators, and families. Participants will review two case vignettes—one male and one female—who initially accepted an ADHD diagnosis and embraced neurodivergence as an identity before discovering their difficulties were better explained by undiagnosed ASD in addition to the ADHD. The presentation concludes with a review and dedicated time for questions and discussion.