▪ The costs of building and operating open windrow municipal yard trimmings composting facilities of different sizes and levels of technical sophistication are analyzed. Per ton costs of composting are found to be competitive with the costs of operating a lined sanitary landfill. Unpaved, minimal tech facilities are considerably cheaper to build and operate than more sophisticated facilities; however, the low quality of the material produced by such facilities may significantly limit the amount of that product that can be marketed (or even given away). Economies of scale clearly favor more sophisticated systems at larger annual volumes. At lower annual volumes, composting systems featuring specialized equipment like compost turners and shredders are not likely to be cost effective.