These arethe proceedingsof the Fourth InternationalWorkshopon Cooperative Information Agents, held in Boston Massachusetts, USA, July 7-9, 2000. Cooperative information agent research and development focused originally onaccessingmultiple, heterogeneous, anddistributedinformationsources. Ga- ingaccesstothesesystems, throughInternetsearchengines, applicationprogram interfaces, wrappers, and web-based screens has been an important focus of - operative intelligent agents. Research has also focused on the integration of this information into a coherent model that combined data and knowledge from...