Recently states and local communities have passed hundreds of ballot initiatives preserving open space, increasing development around transit, and providing for increased brownfield redevelopment. Each of these places has had different reasons--economic, environmental or community goals--for pursuing a chosen development path. Environmentally, these decisions can help communities reduce vehicular emissions, improve water quality, and remediate contaminated lands. States and communities are interested in accounting for the air quality benefits of their development choices. This guidance presents the conditions under which the benefits of land use activities could be included in air quality and transportation planning processes. The United States Environmental Protection Agency (EPA) intends that this guidance be an additional tool to encourage the development of land use policies and projects which improve livability in general, and air quality in particular. This effort is intended to complement the efforts of states and local areas, and to provide guidance, flexibility and technical assistance to areas that wish to implement these measures and use them towards meeting their air quality goals. The goal of this guidance is to assist air quality and transportation planners in accounting for the air quality impacts of land use policies and projects which state and local governments voluntarily adopt. EPA is providing this guidance to give flexibility to state and local governments by expanding the number of strategies an area can use to meet its air quality planning requirements. Properly modeled and quantified land use activities have the potential to help local areas meet their air quality goals, and impact the quality of life of all citizens. In general, states can account for the air quality benefits of land use activities for nonattainment and maintenance areas in one of three ways: Including land use activities in the initial forecast of future emissions in the SIP; Including land use activities as control strategies in the SIP; and Including land use activities in a conformity determination, without including them in the SIP.