This Guidebook summarizes technical and organizational issues that influence the effectiveness with which spatial data are managed in a transit agency and provides guidance for avoiding and overcoming the barriers that typically pose problems for transit with respect to spatial data. Specifically, this Guidebook presents a set of "best practices" that minimize location-referencing problems and support effective spatial data usage. Given new tools and best practices information, transit agencies will benefit as spatial databases are built and expanded, as Geographic Information System (GIS) and ITS applications are installed and as ITS applications are maintained and operated.