This report analyzes approaches taken by state departments of transportation (DOTs), their local partners, and other project sponsors to satisfy National Environmental Policy Act (NEPA) requirements for transportation projects involving more than one mode. Specific objectives of the research were to: 1) characterize the challenges inherent in satisfying the NEPA requirements of multiple U.S. DOT agencies; 2) identify strategies and tactics that state and local transportation agencies have used to overcome these challenges; and 3) suggest new and innovative strategies that can be applied by state and local transportation agencies in future multimodal NEPA processes. Twelve case studies illustrate successful practices and provide examples of institutional arrangements used to comply with NEPA requirements for two or more U.S. DOT agencies. The case studies demonstrated that there is no single best way to approach the NEPA process for multimodal situations. Success may depend more on the willingness and motivation of the agencies to work together, to find common ground, and to work around differing processes, and less upon a specific organizational structure. An effective interagency approach depends on how well the project sponsor and other agencies are able to work together and bridge their procedural differences.