Originally published in 1973, the main objectives of this study were to bring together a comprehensive amount of empirical information on the structure and process of interest groups and the nature of their interaction and influence vis-á-vis government (a great deal of such information existed regarding the USA but the subject had been somewhat neglected in the case of Canada) and also to provide a theoretical explanation of interest groups in the political process by a comparative analysis of their behaviour in the two different political and cultural systems of Canada and the USA. The implications of the study are developed within the framework of the theory of elite accommodation, which attempts to explain interest-group behaviour in the context of the larger socio-political system. Arguing that Canada should be included in the category of 'consociational' societies - i.e. relatively stable societies characterised by deep cleavages of religion and ethnicity, such as Belgium, the Netherlands and Switzerland - the author shows how accommodation between governmental and private elites encourages democratic stability in Canada in two ways: in a 'nation-saving' context and also on the operational level of allocating social resources.