The purpose of this report, which was prepared for the U.S. Environmental Protection Agency, is to present a catalog of the economic advantages and disadvantages of decentralized wastewater systems relative to larger-scale solutions, in order to inform wastewater facility planning and assist communities in making better choices among their many technology options. To this end, this study attempts to compile and summarize what is known about the comparative benefits and costs of various aspects of centralized and decentralized systems. It also reveals and discusses the many issues that should be addressed when site-specific wastewater facility plans are prepared, as an annotated check-list that will help engineers, planners, and other professionals facilitate a more informed discussion of the advantages and disadvantages of various system options for the communities they serve.