With the cooperation of the City of Philadelphia Department of Streets and Department of Public Health, the characterization and classification of incinerator residue was studied. The authors examined the following objectives: To establish procedural criteria for the rapid examination and evaluation of physical, chemical, and biological characteristics; to determine potential public health nuisance conditions resulting from placing incinerator residue in land fills with particular attention to rodent attraction and propogation, fly and insect breeding, odor eminations, wind and water erosion, and stream pollution; to determine the effect of the incinerator on the physical, chemical, and biological characteristics of residue; and to determine the maximum amount of leachable material in incinerator residue.