Objective: To determine whether impulsive aggression (IA) is a meaningful clinical construct and to ascertain whether it is sufficiently similar across diagnostic categories, such that parallel studies across disorders might constitute appropriate evidence for pursuing indications. If so, how should IA be assessed, pharmacological studies designed, and ethical issues addressed? Method: Experts from key stakeholder communities, including academic clinicians, researchers, practicing clinicians, U.S. Food and Drug Administration, National Institute of Mental Health, industry sponsors, and patient and family advocates, met for a 2-day consensus conference on November 4 and 5, 2004. After evaluating summary presentations on current research evidence, participants were assigned to three workgroups, examined core issues, and generated consensus guidelines in their areas. Workgroup recommendations were discussed by the whole group to reach consensus, and then further iterated and condensed into this report post-conference by the authors. Results: Conference participants agreed that IA is a substantial public health and clinical concern, constitutes a key therapeutic target across multiple disorders, and can be measured with sufficient precision that pharmacological studies are warranted. Additional areas of consensus concerned types of measures, optimal study designs, and ethical imperatives. Conclusion: Derived from scientific evidence and clinical experience, these consensus-driven recommendations can guide the design of future studies. (Contains 2 tables and 2 figures.)