This paper investigates organizational mortality in the early American telephone industry, in which thousands of companies proliferated and failed under conditions of technological change. Drawing on the theory of community ecology, it is predicted that when technologies are systemic, technological change does not necessarily favor advanced organizations. Instead, mutualism is predicted among both advanced and primitive firms, as long as they are technologically standardized and differentiated. Competition is expected when organizations are technologically incompatible or noncomplementary. The hypotheses are supported by dynamic models of organizational mortality, estimated using archival data describing the life histories of all telephone companies that operated in Pennsylvania up to 1934 and in southeast Iowa from 1900 to 1930.