Crucial to the design of multi-purpose GIS is the identification of semantical differences and commonalties between the concepts held by participants. Design involves communication between the diverse groups of participants as they mitigate their differences, find common understandings, and find coherency. It is a process of negotiating semantics. The socio-technological design methodology I present here, participatory design, is a process of negotiation and construction involving participants cultures. This process of elaborating semantics retains the essential characteristics of each culture's world-view and simultaneously connects and relates a wide range of aspects. Drawing on sociology of science literature, I refer to the artifacts and concepts that connect different cultures and world-views as boundary objects. As commonalties, portals, or differences, they represent points of tangency between different cultural, disciplinary, and organizational world-views. Through metaphors and morphisms, boundary objects are refined as the basis for collective and collaborative action. In this paper I review the underlying theoretical work on boundary objects and describe its extension for multi-purpose GIS design. For an example of multi-purpose and multi-participant GIS I show how participative design can aid GIS design by finding semantical coherency for stable multi-purpose GIS.