A planning committee convened by the Forum on Microbial Threats of the National Academies of Sciences, Engineering, and Medicine held a virtual workshop on February 23-25, 2021, titled Systematizing the One Health Approach in Preparedness and Response Efforts for Infectious Disease Outbreaks. The workshop gave particular consideration to research opportunities, multisectoral collaboration mechanisms, community-engagement strategies, educational opportunities, and policies that speakers have found effective in implementing the core capacities and interventions of One Health principles to strengthen national health systems and enhance global health security. This Proceedings of a Workshop summarizes the presentations and discussions of the workshop.