TRB’s Transit Cooperative Research Program (TCRP) Web Document 26: TravelMatters: Mitigating Climate Change with Sustainable Surface Transportation reviews TCRP Project H-21: Combating Global Warming with Sustainable Surface Transportation Policy, which created a research report (TCRP Report 93) and TravelMatters Website with information for individuals and transit agencies on the greenhouse gas reduction potential of the public transportation sector. The report also summarizes TCRP Project H-21A, which encourages better decision making by enabling transit professionals and the public to consider both the greenhouse gas and criteria air pollutant impacts of transit planning decisions.