Agencies serving the estimated 42,000 to 137,000 migrant and seasonal farmworkers in the Lake States (Wisconsin, Michigan, and Minnesota) face distinct challenges, including inadequate access to farmworker data to address their needs. This project developed and evaluated a geographical information system (GIS) database for compiling and displaying existing farmworker data in the Lake States. A three-step study was conducted in the Lake States: (1) a preliminary resource and needs assessment was conducted among agencies serving farmworkers, (2) a GIS product was created using data available from state agencies, and (3) the GIS product was evaluated by an advisory board of qualified occupational health and safety representatives for appropriateness, applications, and ease of use. Agencies participated by sharing their available farmworker data. The GIS product consisted of a CD-ROM with data displayed in a graphic format and downloadable spreadsheet files consolidated by county demographic, crop, housing, and migrant health clinic information. Evaluators of the GIS product found it to be an accessible, unique clearinghouse for farmworker-related data. The GIS product can become a valuable tool for agencies serving farmworkers and those researching farmworker-related issues. Agencies and health professionals require useful and comprehensive databases to track and serve farmworkers, and a multi-agency partnership using GIS technology could provide this capability. Further research is required with improved definitions and resources to apply the GIS product.