School-based commercialism exists whenever a district enters into a relationship with a business that provides access to students or staff in exchange for fiscal or in-kind resources (i.e., goods or services). The practice includes business sponsorship of school activities (e.g., sporting events), exclusive agreements (e.g., pouring rights contracts), appropriation of school space (e.g., scoreboards), electronic marketing (e.g., Channel One), fundraising (e.g., candy sales), and the use of sponsored educational materials. Some hold that commercial activities offer districts a much needed means to supplement their resources. Others charge that school-based commercialism needlessly subjects children to unhealthy products and promotions. Given these opposing viewpoints, we find it surprising that little is known about the nature and efficacy of school-based commercialism. Thus far, the literature offers state and local policymakers only anecdotal answers to the following important questions: What is the nature and extent of commercial activities in our schools? What are the monetary and nonmonetary benefits and costs of school-based commercialism? Does school-based commercialism improve or worsen equity? Using multiple methods to analyze data from Pennsylvania and New York school districts, this study shows, for example, that the net benefits of commercial activities are modest at best. The study also shows that districts that engage in commercial activities are poorer, exert greater local effort, and spend less than those that do not. The implications of these and other findings are discussed. (Contains 14 tables and 6 footnotes.)