Sediments contaminated with toxic chemicals such as polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), metals, and metalloids can be found in marine and estuarine bays, harbors, lakes, wetlands, and rivers. SERDP and ESTCP are addressing a wide variety of issues relevant to managing contaminated sediments in place and assessing the processes that govern ecological and human health risks.