The theory of price and quality decision-making in industries with a few firms which recognize their mutual interdependence is of increasing interest to economists and policy makers. This book introduces a novel theory of that decision-making, based upon the notion of the industry as a community of agents who are involved in both competitive and cooperative relationships. It develops theories and illustrates methodological approaches to the analysis of price and quality decision-making in such instances of a ''rivalrous consonance of interests'' among firms.