Throughout much of its history, the United States was predominantly a rural society. The need to provide sustenance resulted in many people settling in areas where food could be raised for their families. Over the past century, however, a quiet shift from a rural to an urban society occurred, such that by 1920, for the first time, more members of our society lived in urban regions than in rural ones. This was made possible by changing agricultural practices. No longer must individuals raise their own food, and the number of person-hours and acreage required to produce food has steadily been decreasing because of technological advances, according to Roundtable member James Merchant of the University of Iowa. The Institute of Medicine's Roundtable on Environmental Health Science, Research, and Medicine held a regional workshop at the University of Iowa on November 29 and 30, 2004, to look at rural environmental health issues. Iowa, with its expanse of rural land area, growing agribusiness, aging population, and increasing immigrant population, provided an opportunity to explore environmental health in a region of the country that is not as densely populated. As many workshop participants agreed, the shifting agricultural practices as the country progresses from family operations to large-scale corporate farms will have impacts on environmental health. This report describes and summarizes the participants' presentations to the Roundtable members and the discussions that the members had with the presenters and participants at the workshop.