Older adults use emergency departments (EDs) more than any other age group and are more prone to subsequent adverse events. This article reviews the literature on ED use by older adults within the context of evaluating their need for emergency care and the extent to which access to primary and supportive care services affect use. While a substantial research literature describes general patterns of ED use, there is much less research on ED use as a function of other health service use. Gaps in the research literature result in a limited understanding of the full scope of the issue and opportunities for practice and policy intervention.