With nearly 20 million inhabitants, 3.5 million vehicles, and 35,000 industries, Mexico City consumes more than 40 million liters of fuel each day. It is also located in a closed basin with a mean altitude of 2240m. The combination of these and other factors has led to a serious air quality problem. In 2002, Mexico City air quality exceeded local standards for ozone (110 ppb for 1 hour) on 80% of the days of the year. Particulate 24- hour standards were exceeded on 5% of the days (SMA, 2002). Greenhouse gas (GHG) emissions from Mexico City are also significant. In 1998, Mexico ranked as the 13th largest GHG producing nation. Mexico City emits approximately 13% of the national total (Sheinbaum et al., 2000). Using a 3.3% annual growth rate (West et al., 2003) and a 1996 base year estimate of 45,585,000 tons of CO2 (Sheinbaum et al., 2000), we estimate that the annualized GHG emission of Mexico City for the period 2003-2010 and 2003-2020 will be 17 million tons of C equivalent per year and 20 million tons C equivalent per year, respectively. As emissions of GHG and local air pollutants are often generated from the same sources, there may exist opportunities for their joint control. In this study, we have developed a cost-benefit analysis framework to analyze the trade-offs between costs, public health benefits, and GHG emission reductions for a select set of control measures. In an effort to disseminate the knowledge collected in this work, we have also created a reduced-form analysis tool for use by policy makers. This study fits into an ongoing process of analysis and action regarding Mexico City air quality. At present, Mexico City government is currently in the process of implementing its third air quality management plan. The first plan, PICCA (Programa Integral para el Control de la Contaminacion Atmosferica) was initiated in 1990 and had several major accomplishments, including the introduction of two way catalytic converters, the phase out of leaded gasoline, and establishment of vehicle emissions standards. The second program, PROAIRE (Programa para Mejorar la Calidad del Aire en el Valle de Mexico 1995-2000) achieved the introduction of MTBE, restrictions on the aromatic content of fuels and reduction of sulfur content in industrial fuel. While significant improvements in ambient air quality have improved, levels remain dangerously high, therefore the government has recently initiated the third plan, PROAIRE 2002-2010, as an extension of previous plans.