Democratic participation (conventional and unconventional methods of legal political activity in democracies) and aggressive participation (civil disobedience and political violence) are analytically distinct types of political behaviour. Previous explanatory models have assumed (usually implicitly) that these types of behaviour are uncorrelated. But an accumulation of recent research evidence shows them to be correlated expirically; therefore an important current priority of political participation research is development of integrated model to explain both types. Using 1974 survey data from the Federal Republic of Germany. a preliminary simultaneous-equation model is specified and tested.