The post-September 11 era has prompted unprecedented attention to medical preparations for national special security events (NSSE), requiring extraordinary planning and coordination among federal, state, and local agencies. For an NSSE, the US Secret Service (USSS) serves as the lead agency for all security operations and coordinates with relevant partners to provide for the safety and welfare of participants. For the 2004 Democratic National Convention (DNC), designated an NSSE, the USSS tasked the Boston Emergency Medical Services (BEMS) of the Boston Public Health Commission with the design and implementation of health services related to the Convention. In this article, we describe the planning and development of BEMS' robust 2004 DNC Medical Consequence Management Plan, addressing the following activities: public health surveillance, on-site medical care, surge capacity in the event of a mass casualty incident, and management of federal response assets. Lessons learned from enhanced medical planning for the 2004 DNC may serve as an effective model for future mass gathering events.