Whole organism bioassays for the assessment of soil, freshwater sediment, and freshwater quality were evaluated for their application in the assessment and remediation of contaminated sites in Canada under the National Contaminated Sites Remediation Program. Using 3 essential and 12 desirable methodological criteria, bioassays were categorized as currently usable, prototype, or under development. Based on further considerations related to bioassay application, a battery of usable screening and definitive tests was recommended (with suggestions for augmentation) for each medium. Of the 18 bioassays reviewed for soil quality assessment, 6 were usable, 5 were prototypes, and 7 were under development. Battery screening and definitive tests included 14-day Eisenia andrei survival, 120-hr lettuce and radish seedling emergence, and 72-hr Selenastrum capricornutum growth inhibition. Augmentation with the following bioassays was recommended: soil/freshwater bacterial growth, arthropod reproduction, earthworm reproduction, and reproduction of other soil-dependent organisms. Of the 9 bioassays reviewed for freshwater sediment quality assessment, 1 was usable, 2 were prototypes, and 6 were under development. Three bioassays in the latter two groups were considered usable with the imminent completion of research underway. Screening tests selected included 10-day Chironomus tentans survival, 10-day Hyalella azteca survival, 10-day Hexagenia spp. survival, and 72-hr S. capricornutum growth inhibition. Definitive tests included screening tests, substituting 28-day H. azteca sexual maturation for 10-day survival. Augmentation with the following bioassays was recommended: sediment/freshwater bacterial test, 28-day Tubifex tubifex reproduction, and rooted aquatic plant growth. Of the 25 bioassays considered for freshwater quality assessment, 8 were usable, 7 were prototypes, and 10 were under development. Screening tests selected included 72-hr S. capricornutum growth inhibition; 48-hr Daphnia sp. survival, and 5- and 15-min Photobacterium phosphoreum bioluminescence. Definitive tests included first screening test, 7-day Ceriodaphnia dubia, 7-day fathead minnow larval survival, or 96-hr rainbow trout survival. Augmentation with the following bioassays was recommended: Brachionus calyciflorus 24-hr survival, 48-hr reproduction; freshwater bacterial growth; and aquatic vascular plant growth.