TRB’s Airport Cooperative Research Program (ACRP) Report 56: Handbook for Considering Practical Greenhouse Gas Emission Reduction Strategies for Airports is designed to assist airport operators in identifying, evaluating, prioritizing, and implementing practical, low-cost strategies to reduce and manage greenhouse gas emissions. AirportGEAR, an interactive decision support tool developed as a companion to the handbook, considers a range of strategies that can be implemented by all types of airports—regardless of size, geography, or resources—either directly or in partnership with airport stakeholders, including airlines, airport tenants, and host communities. AirportGEAR is on a CD-ROM that is included with the print version of ACRP Report 56