This article is an edited version of an address before the Great Lakes Pollution Monitoring Workshop sponsored by the National Oceanic and Atmospheric Administration (NOAA) in Ann Arbor, Michigan, February 11-12, 1981. Current and historical efforts in Great Lakes monitoring are reviewed. The contributions of the Great Lakes Information and Surveillance Plan (GLISP) to existing knowledge of the ecosystem are discussed. An ecosystem approach to toxic substances in the Great Lakes is presented and recommendations for implementing the surveillance plan for consideration of toxic organic substances are made.