The computer-based strategy tradeoff model has been developed to evaluate alternative strategiesfor meeting regional air quality standards, to help select minimum total cost strategies, and to analyze (parametrically) the sensitivity of the results to key assumptions. Data requirements are modest. The user specifies the air quality standard to be achieved plus a menu of possible strategy components and the tradeoff model then finds the combination of strategy components that meets the desired air quality standard for the minimum total cost (expenditures plus the social cost of trips foregone). It also calculates a variety of other impacts. Regional air quality control strategies are considered by the tradeoff model to consist of three primary components. These are additoinal fixed source controls, retrofit emission control devices and inspection/maintenance programs for in-use vehicles, and transportation management controls. The cost and effectiveness of the fixed source controls and various in-use vehicle retrofit-inspection/maintenance strategies are determined by separate analysis, and are subequently provided as inputs to the tradoff model. Tradeoff incorporates the Policy-Oriented Transportation Model as a subroutine and uses it to estimate the impacts of the transprotation management controls. These controls include bus system improvements, regional mileage surcharges or limitation, induced changes in auto occupancy, and induced changes in traffic congestion. Section I. Introduction -- Section II. Determing the emission constraint -- Section III. Strategy-evaluation mode -- Section IV. Strategy-selection mode -- Section V. Concluding remarks.