Periods of social and political change often are marked by struggles among competing ideologies. Given the importance of formal organizatons to such struggles, we propose that competitions among ideologies can be understood and modeled as an ecology of organizations. In this spirit, we develop a model of ideological competition among organizations, and investigate our ideas using data on newspapers in Vienna over the period 1918 and 1938. This was period of considerable social and political change in Vienna. 1918 saw the birth of so-called Red Vienna, a model socialist municipality, but within only a few years economic crises and political changes led to an increasing and better-organizaed right-wing movement. By 1934 the forces of right and left in Vienna were mobilized and in February a brief civil war erupted, from which the socialist did not recover. Mirroring these changes in circumstances, Viennese newspapers were founded and failed at high rates. Many newspapers survived through the Anschluss in 1938, but 104 newpapers— nearly 3/4 of the population — failed over the period 1918-1938. By analyzing the rates of failure and growth among these organizations, we estimate an ecological model of ideological competition. The results demonstrate the usefulness of our model of ideological competition. The results demonstrate the usefulness of our model in predicting how ideological similarities and differences affect organizational fates.