A major theoretical issue in the study of language processing and language acquisition is whether language development is independent of other aspects of cognitive development, encapsulated in a "language module." This issue is discussed as it relates to lexical processing. The paper begins with a historical contextualization of the modular view of the mind and a general discussion of language processing from a modular perspective. It then considers and critiques some arguments in favor of modularity based on neurolinguistic data, before examining the cases for and against the notion that the formal aspects of lexical processing are "informationally encapsulated." Finally, it discusses the relevance of the modularity concept to lexical processing. (MSE)