In an era of social welfare reform marked by the erosion of a societal safety net, few institutions remain that can guarantee assistance to those most in need. The hospital emergency department is perhaps the only local institution where professional help is mandated by law, with guaranteed availability for all persons, all the time, regardless of the problem. Although the ED serves as a true social safety net, its potential as a social welfare institution generally goes underestimated, hampering its full development as an effective societal resource. More of the disadvantaged may pass through the ED than through any other community institution, making it a logical site not only for the treatment of acute illness, but also for the identification of basic social needs and the extension of existing community resources. By helping more fully incorporate the ED into the total care of its community, emergency physicians can become leaders in the design and implementation of integrated sociomedical systems of care.