Limited data are available regarding the occurrence of potentially hazardous constituents in raw, uncomposted yard wastes, partially composted yard wastes, and finished compost (15, 16). Environmental monitoring at composting operations or facilities is lacking, and currently published research on the environmental fate of composted yard waste constituents is extremely limited. The cost of thoroughly investigating the fate of toxicants in yard waste may seem needlessly expensive, but it is much less than the cost of cleaning up contaminated sites and groundwater. Could yard waste compost sites become Superfund sites? The cost of a thorough testing program throughout the United States may be several million dollars, but that is only a fraction of the funds spent initiating and developing yard waste composting facilities, let alone the potentially much greater cost of environmental remediation. There is still time to address these problems and to develop sound state and federal guidelines for siting and operating yard waste compost facilities. The rush to implement landfill alternatives such as composting should not be the major driving force in determining legislation governing solid waste management. ?? 1991 American Chemical Society.