U.S. Environmental Protection Agencys (U.S. EPA) mission is to protect human health and to safeguard the natural environment upon which life depends. Sediments are an integral component of aquatic ecosystems, and contaminants in sediments pose a threat to human health, aquatic life, and the environment. Humans, aquatic organisms, and other wildlife are at risk through direct exposure to pollutants or through consumption of contaminated fish and wildlife. Exposure to these contaminants is linked to cancer, birth defects, neurological defects, immune dysfunction, and liver and kidney ailments. Contaminated sediments may also cause economic impacts, at both the local and regional level, on the transportation, fishing, tourism, and development industries. Sediment contamination is an issue that cuts across offices and jurisdictions throughout the Agency, other Federal agencies, state agencies, and tribes. In response to the cross-cutting and multi-faceted dimensions of the issue, U.S. EPAs Science Policy Council (SPC) initiated in 2000 the development of the Contaminated Sediments Science Plan (CSSP or the Plan). The CSSP is intended as a mechanism for the U.S. EPA to develop and coordinate Agency-wide science activities in the contaminated sediments area. Along with the EPA's contaminated sediments science activities database, this plan provides an analysis of the current Agency science activities in this area, identifies and evaluates the science gaps, and provides a strategy for filling these gaps.