This research examines the development of modern firefighting methods, equipment, and institutions in London and Amsterdam in the seventeenth and eighteenth centuries and Salem (Massachusetts) and Boston in the eighteenth to mid-nineteenth centuries. Modern firefighting is characterized as organized firefighting efforts based on mobile water pumps—fire engines—rather than bucket brigades and other spontaneous actions. The growth of city size and density increased the threat and extent of fire damage, providing incentives to devise more effective means of controlling fires; technical innovations, particularly those of continuous-stream water pumps and flexible hose, enabled the development of more useful fire engines. But without innovations in the organization and institutional sponsorship of firefighting efforts, these factors alone were not sufficient to effect the transition to modern firefighting. The complex sets of public and private interests threatened by urban fires, combined with the technical logistics of firefighting, required novel—but not singular—forms of organization and institutional sponsorship. Furthermore, firefighting provided institutions undertaking firefighting roles with opportunities to achieve a variety of secondary objectives that often had little to do with putting out fires. More generally, controlling fires presented unique technical problems as well as opportunities within communities for the expression of social and cultural values and for negotiating the boundaries of public goods. The comparative approach taken in this research better demonstrates the relationship between what was technically feasible and what was institutionally desirable than would be possible by examining only one community.