Chapter I: "Background and Description of Regional Library Development in Ontario," aimed at placing the perspective of centralized processing within the framework of cooperative effort, presents some general discussion of these two concepts. The Ontario plan, and the relationship of the Midwestern Regional Library System and its Centralized Processing Center, is then mirrored against this background. Chapter II: "Centralized Processing," reviews the background, operation, and production of the Center. Recommendations concerning space, layout of work and staff are given. Chapter III: "User Attitudes," focuses on the evaluation of the work of the Processing Center by the participating libraries and their reaction to the product of the Center. Chapter IV: "Regional Library Activities," summarizes attitudes and ideas on other cooperative projects for the Region. (NH)