A relatively small subgroup of emergency department (ED) patients is responsible for a disproportionate amount of ED visits and costs. This subgroup, the heavy users of ED services, is identified as a medically and socially vulnerable population. Heavy users of ED services are identified as a 'problem' in the United States that opens a 'window' on the wider social issues critical to consensus on health care reform. The problem is nested within a complex of larger, interdependent problems including access to care, lack of primary/preventive services, absent or inadequate social services, and fragmented service delivery. This article uses the literature on heavy users of ED services to argue that social constructions of the problem and articulation of solutions by different key players in health care reform are based on divergent and often conflicting premises.