The cost of producing the same good often differs substantially for public and private producers. We investigate the effect of organization in a case where the production technology is simple: The cleaning of Danish schools. Three forms of organization are used: Decentral municipal, central municipal or private. For small schools the organizational form has little impact on cost. For larger schools decentral municipal production is the most expensive. On average centralization reduces costs by 5%, while privatization reduces costs by 30%. Similar cost differences are reported in the literature for other cases, but it is a new result that the cost differences are due to economies of scale. Public choice theories predict that cost differences are due to ownership or competition. We find evidence that both theories help explain the cost differences.