Objective: We appraised whether FDA registration trials for ADHD pharmacotherapy in adults provides comparable information to inform treatment expectations. Method: Comparison of ADHD outcome measure patterns in ADHD pharmacotherapy FDA drug label source studies. Results: Among stimulants, from fixed-dose titration data, amphetamine agents had numerically higher placebo-corrected symptom improvement and symptom effect sizes than methylphenidate agents. Symptom effect sizes were lower in the flexible dosing registration studies of atomoxetine and viloxazine. Varying responder definitions were analyzable, based on [greater than or equal to] 30% symptom improvement and/or CGI-I improvement of "much" or "very much improved." Number of exposures needed to create these responses were lower for stimulants than for viloxazine. Conclusion: Heterogeneity in the design and analysis of FDA drug label source trials restricts implications for clinical practice. Research conducted using replicated designs, direct comparison of available treatments, and outcome analyses that generalize to clinical care could better inform clinical decision making. "(J. of Att. Dis. 2024; 28(5) 800-809)"