This article examines Bus Rapid Transit (BRT) as a near-term strategy for reducing CO2 emissions in a typical medium-sized U.S. city. The paper compares the expected CO2 emissions from three scenarios to meet the city’s growth in work trips by 2011: a no-build option that relies upon private automobiles and a diesel bus fleet; building a light rail (LRT) system; and building a BRT system using 40-ft or 60-ft low emission buses. The paper calculates a CO2 emissions inventory for each scenario and finds that BRT offers the greatest potential for greenhouse gas reductions, primarily because BRT vehicles generally offer lower CO2 emissions per passenger mile than LRT. Lower capital costs for BRT infrastructure would enable cities to build more BRT than LRT for a given budget, increasing opportunities to shift commuters to public transit. Further study to enhance a methodology to estimate expected CO2 reductions with BRT would be valuable.