The focus of geographic and other ontologies of urban devel- opment has been to represent locations with object attributes or objects with locational attributes. Urban information systems should also repre- sent decisions, which have or could have locational attributes. Develop- ment processes are critically influenced by expectations about declared intentions manifest through plans and records of decisions. This paper provides an ontology of decision situations characterized by actors par- ticipating, intentions expressed, and alternatives considered. We argue that these elements are closely tied to and interdependent with other aspects of urban ontologies, which typically focus on physical objects of development. An ontology of plans and decisions will enable sharing of information among actors and consideration of disparate and distributed information.