Many adult ADHD assessments are conducted within ADHD-specific frameworks that do not fully account for the high rates of co-occurring autism. As a result, clinicians may overlook clinically meaningful patterns, misattribute traits, or provide recommendations that do not fully match the individual’s neurodevelopmental profile. This session introduces a neurodiversity-affirming approach to adult ADHD assessment that integrates autism competency into clinical decision-making. Participants will learn how traits associated with autism and ADHD can mask, compensate for, or distort one another, particularly in high masking adults. For example, executive functioning differences, sensory sensitivities, and social communication patterns may be misattributed or overlooked entirely when clinicians rely on single-diagnosis frameworks. This “mutual masking” dynamic contributes to missed or partial identification, especially in late-diagnosed and high-achieving individuals. Attendees will be guided through a structured framework for differentiating ADHD, autism, and co-occurring presentations in adults, with particular attention to high-masking and late-identified individuals. The session will also outline practical modifications to intake, interview structure, and feedback practices that improve diagnostic clarity and clinical utility. Participants will leave with concrete tools, including targeted screening questions, differential indicators, and language shifts that can be immediately applied in assessment and treatment planning.