disambiguation of proper names in text identifying the occurrences of proper names in text and the entities they refer to can be a difficult task because of the many-to-many mapping between names and their referents. we analyze the types of ambiguity -- structural and semantic -- that make the discovery of proper names difficult in text, and describe the heuristics used to disambiguate names in nominator, a fully-implemented module for proper name recognition developed at the ibm t.j. watson research center. we use hand-written rules and knowledge bases to classify proper names into broad categories.