Research on sources of PCB's and levels in school environments is needed to improve risk management decisions. To better understand the significance of PCB-contaminated caulk as a source of exposures to children, teachers, and staff in school buildings, the U.S. Environment Protection Agencys (EPAs) Office of Research and Development (ORD) plans to do the following: (1) characterize PCB-contaminated caulk and other potential sources of PCBs in schools; (2) investigate relationships between PCB concentrations in air, on surfaces, and in dust and soil with potential sources in school buildings; (3) evaluate which routes of exposure (e.g., inhalation, contact with surfaces or dust) are likely to be most important; (4) improve exposure assessment models for schoolrelated exposures and examine the feasibility for development of an indoor model for PCBs; and (5) provide samples, data, and other information to assist in developing risk management practices for reducing exposure to PCB's in schools. To meet these research objectives, the ORD National Exposure Research Laboratory (NERL) plans to conduct a measurement study in up to nine schools in the United States. The research described in this study design is being coordinated with research efforts in the ORD National Risk Management Research Laboratory (NRMRL) that are aimed at evaluating PCB emission rates, transport, and exposure mitigation methods.