High-consequence surge research involves a systems approach that includes elements such as healthcare facilities, out-of-hospital systems, mortuary services, public health, and sheltering. This article focuses on one aspect of this research, hospital surge capacity, and discusses a definition for such capacity, its components, and future considerations. While conceptual definitions of surge capacity exist, evidence-based practical guidelines for hospitals require enhancement. The Health Resources and Services Administration's (HRSA) definition and benchmarks are extrapolated from those of other countries and rely mainly on trauma data. The most significant part of the HRSA target, the need to care for 500 victims stricken with an infectious disease per one million population in 24 hours, was not developed using a biological model. If HRSA's recommendation is applied to a sample metropolitan area such as Orange County, California, this translates to a goal of expanding hospital capacity by 20%-25% in the first 24 hours. Literature supporting this target is largely consensus based or anecdotal. There are no current objective measures defining hospital surge capacity. The literature identifying the components of surge capacity is fairly consistent and lists them as personnel, supplies and equipment, facilities, and a management system. Studies identifying strategies for hospitals to enhance these components and estimates of how long it will take are lacking. One system for augmenting hospital staff, the Emergency System for Advance Registration of Volunteer Health Professionals, is a consensus-derived plan that has never been tested. Future challenges include developing strategies to handle the two different types of high-consequence surge events: 1) a focal, time-limited event (such as an earthquake) where outside resources exist and can be mobilized to assist those in need and 2) a widespread, prolonged event (such as pandemic influenza) where all resources will be in use and rationing or triage is needed.