There can be little argument that contaminants are now a ubiquitous presence in our environment. Though large-scale efforts to deal with contaminant issues have traditionally focused on water and air media, it has become increasingly apparent that contaminated soil is also placing human and environmental health at risk, not only in Canada but world-wide. ln response to the urgency of the problem, large-scale national programs such as the U.S. EPA Superfund and Canada's National Contaminated Site Remediation Program (NCSRP) have been created to promote the cleanup of high priority contaminated sites. Implementation of such programs presents unique regulatory and scientific challenges in the development of an effective and scientifically-defensible infrastructure to guide the assessment and remediation of contaminated soils. This challenge is accentuated not only by the short time-frame over which these programs have been developed and the broad range of contaminants and sources that must be dealt with, but by a still evolving understanding of the effects of contaminants in the complex soil environment and on the myriad of uses it sustains.