Originally published in 1974, this volume presents the results of a five-year study, funded by the Canada Council, the main objectives of which were to assemble a comprehensive amount of empirical information on the structure and process of interest groups and the nature of their interactions and influence vis-à-vis government, and to provide a theoretical account and explanation of interest groups in the policy-making process by a comparative analysis of their behavior in two different political systems, i.e. parliamentary and presidential. Three elite groups (interest group executives, legislators, and higher civil servants, numbering 2400 in all), were interviewed at length in eight areas: Washington D.C., Michigan, Louisiana, Washington State, Ottawa, Ontario, Quebec, and British Columbia, which made this the most ambitious cross-national comparative investigation of interaction and policy-making yet undertaken.