Identifying the occurrences of proper names in text and the entities they refer to can be a difficult task because of the manyto-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. 1 Proper Name Identification in Natural Language Processing Text processing applications, such as machine translation systems, information retrieval systems or natural-language understanding systems, need to identify multi-word expressions that refer to proper names of people, organizations, places, laws and other entities. When encountering Mrs. Candy Hill in input text, for example, a machine translation system should not attempt to look up the translation of candy and hill, but should translate Mrs. to the appropriat...