ABSTRACTThe relationship between ecological structures and political radicalism is a long‐pursued but little‐systematized topic among political sociologists. Only recently are we becoming aware of the fact that many of the difficulties in this area actually arise from metascientific preconceptions rather than from the processes themselves. Erik Allardt's analyses of radicalism in Finland are perhaps the best illustration of both the promise and problems of political ecology, and his theories, methods, and metaperspectives are used here as the backdrop for analysing Norwegian data.One of Allardt's more recent six‐fold models is applied to the well‐known emergence of Norwegian radicalism between 1900 and 1921. Factor analysis, incorporating both synchronic and diachronic indicators, is used to test the model and the results show a considerable amount of success in predicting the structural basis of radical socialism. Predictors as tomoderatesocialism prove to be more problematical, however, and it is in the context of this problem that the general relationship between “structural” and “cultural” explanations is taken up. A deeper analysis of the Norwegian case leads to the conclusion that both types of explanation are, or at least should be, complementary turns of a more fundamental res