Abstract: The practical outcome of the project, Analysis of the Organization of Lexical Memory, is an electronic lexical database called WordNet that can be incorporated into computer systems for processing English text. WordNet includes approximately 45,000 lexicalized concepts, providing a coverage equivalent to a hand held dictionary. The database has three components, one each for nouns, verbs, and adjectives. The semantic relations that organize each component are different, but in general a lexicalized concept is represented by a set of synonyms that can be used to express the concept, the familiar semantic relations are represented by labeled pointers between synonyms sets. In order to create the database, programs were written to write and edit lexical files, to convert lexical files into database, to search the database, to strip inflections from search requests, and to display retrieved information for a user. Three user interfaces have been developed for WordNet. (1) The simplest is a command line version that does not require a windowing system and can run on standard monitors. (2) A browser written for Sun View and for X-11 windows is intended for use with an on-line dictionary; by using WordNet, the dictionary can be searched conceptually as well as alphabetically. (3) A lexical filter written for X-11 windows catches unfamiliar words in a text file and suggests alternative expressions that an author may wish to choose.