The lexicon of present-day English is changing rapidly and regularly, and a description and explanation of this change is necessary for any comprehensive diachronic theory. An examination of a corpus of 500 new words collected during 1975 provides the basis for a typology of lexical change that both supports and suggests modifications for the theories of language change of Weinreich, Labov, and Herzog (1968) and Samuels (1972). The rarest neologisms are nonce words and words created from scratch (zero-derivatives); somewhat more common are words consisting of new or uncommon morphs combined with more ordinary ones. Least rare are new combinations of old morphs; borrowings from other languages, cultures, or specialized or non-elite dialects; words created by analogy; and words modified to fit new syntactic slots. Words may simply have their semantic range altered, or existing words may fossilize in phrases acting as single semantic units. Lexical change usually involves material already present in the language system or in that of a contact system. It occurs in all idiolects and registers in response to definable linguistic forces, in various degrees of consciousness; and its diffusion, while not necessarily predictable, can be mapped according to a number of specific linguistic, social, and psychological variables. Particular attention is paid to the neutralization of sex references where they are not contextually relevant. (Author/KM)