This paper investigates the unique challenges of an expanding group of stakeholders making demands upon shared geospatial data resources: non governmental organisations participating in local governance. In spite of efforts to improve local data integration in spatial data infrastructures and development of strategies from public participation GIS to expand access to geospatial data and technologies, grassroots data users still experience difficulties with the accessibility, quality, and usefulness of local government data resources. Drawing from extended ethnographic research conducted in Chicago, Illinois, I illustrate these problems and how they are shaped by grassroots groups' resource constraints, knowledge systems, and socio-political positions; and assess the feasibility and impacts of proposed alternatives for better meeting grassroots spatial data needs. I contend that the needs and challenges of these stakeholders are unique from those of other users, but are nonetheless rooted in central dilemmas of spatial data handling, and so might be addressed through stronger engagement with GIScience research in this arena.