Abstract Geographic information systems (GIS) offer public health nurses a new technology to plan and implement interventions within communities. The present article gives a brief overview of GIS, describes a project designed to pilot-test the use of GIS for developing population-based interventions, and discusses lessons learned from the project that need to be applied to any future work. Using GIS to map the incidence and prevalence of disease, locate risk factors, and identify access to health care services is not difficult. Trying to move beyond that and use the technology to depict community networks and develop and implement population-based interventions is more problematic. The project identified specific questions that anyone involved in a planning or decision-making project in which GIS are used should ask.