This discussion on the interpretation of language and the role of inference argues that language is a tool in the sense that it provides the basic operators and rules of operation for speech just as arithmetic does for calculation. It is suggested that because language is a tool that is restricted in its expressive potential by the linguistic system, speakers often have to rely on inferences made on the basis of the meaning of sentences to get at the messages conveyed, and learn to take advantage of this process to carry on communication. The discussion is divided into the following sections: (1) language is used to say something; (2) the model of saying things; (3) the interpretation of sign meanings; (4) the interpretation of grammatical signs; (5) lexical systems; (6) the interpretation of lexical signs; (7) the role of inference in sign interpretation; (8) logical inference at all levels of language use; (9) inference at the phonological level; (10) inference at the lexical level; (11) inference at the grammatical level; (12) inference at the lexico-grammatical level; and (13) a model for inference in sign and sentence interpretation. (Author/JL)