The challenge of an increasing elderly population, particularly with respect to frail older persons in need of long-term care, has coupled with ever-present budget constraints to make the financing, organization and delivery of elder care a major priority in North America, Europe and elsewhere in the developed world. Despite obvious cross-national differences in health and social care arrangements for the frail elderly, evidence of poorly coordinated services, disjointed care, less than optimum outcomes, system inefficiency, inadequate accountability, and uncontrolled costs can be found in all countries. There is a growing belief that more comprehensive approaches are needed to effectively address these problems. One such strategy, so-called integrated systems of care, shows great promise. The author critically examines the concept of integrated systems of care for the frail elderly, including the theoretical benefits and drawbacks of the model. At the policy and practice levels, descriptions are presented of, and evidence and lessons are summarized from a representative sample of such projects in the US (Social HMO and PACE), Canada (SIPA), Italy (Rovereto) and Australia (Coordinated Care Trials). The introduction of prototypes such as these raises a number of significant issues for policymakers, payers, providers, consumers and researchers. These are briefly examined in concluding remarks on the important potential of integrated systems of care for vulnerable older people.