Assessing risks means understanding the interactions come together to shape complex, uncertain future events. ARTIS’s approach to risk assessment involves the disciplined integration of formal modeling and expert judgment. The formal modeling decomposes complex problems into manageable pieces. The expert judgment allows pooling knowledge from the diverse sources available to ARTIS’s experts. Our transparent process clarifies the bases of our predictions, invites external review, facilities collaborative work, and translates readily into authoritative communications to policy makers. It has been applied across the range of ARTIS’s expertise.