The goal of this proposed research is to develop techniques for the locational planning of sophisticated Emergency Medical Service (EMS) systems, characterized by multiple levels of health services. Ultimately, this investigation is concerned with ways of providing the best possible access of people to a number of different emergency services. By applying location covering techniques within a hierarchical framework, this study develops methods for locating multilevel EMS systems. Specifically, a three-tiered system with "first response," "basic life support," and "advanced life support" capabilities is seen as a common EMS structure which is emerging in a number of medium-to-large scale cities. The principal formulation, then, can be stated as: In a three tiered EMS system with limits on units (ambulances or stations) of p1,p2,p3, and maximum response time standards of s1,s2, s3, for each tier of operation, find the optimal locations of EMS units so as to: a) maximize the amount of demand served by different service levels within their respective response time standards, and b) assure "back-up" coordination between levels in deployment. The second hierarchical formulation of multiple deployment pattens of a single level of facilities can be described as: In a p-unit EMS system with k units unavailable for service, find the (p-k) locations, closest to the original configuration, which maximizes the amount of demand served within S time units.