SERDP and ESTCP sponsored an expert panel workshop to (1) examine the current state of the science and technology for understanding and assessing bioavailability processes in soils and sediments that may impact risk-based remedial action decisions, (2) evaluate current and potential future applications of bioavailability concepts and assess barriers to their implementation, and (3) identify and prioritize research and demonstration opportunities that, if addressed, can facilitate regulatory acceptance and field implementation of bioavailability concepts to support risk assessments at DoD sites.