Using the Denver Air Quality Control Region as a case example, this study examines the costs and benefits associated with the implementation and administration of transportation air quality measures required under the Clean Air Act. The study was undertaken in response to the problems encountered by a number of metropolitan areas in their efforts to implement EPA Transportation Control Plans (TCP's). Program measures examined are vehicle inspection and maintenance, ride sharing, preferential treatment for high occupancy vehicles, parking management, bicycling and transit. Impacts are described on legal and institutional considerations, urban economics, public administration, zoning, land management, travel behavior and conditions, motor vehicle regulation, capital enforcement costs, air quality, energy and safety. Emphasis is placed on the particular groups or institutions affected and on determination of relative importance of various costs and benefits associated with implementation. The report concludes with an assessment of the implications for federal transportation policy. Analysis methodologies are described in a series of technical appendices. A separate Executive Summary is provided.