This book explores the consequences of Chomsky's Minimalist Program for the data of bilingual language mixture. In the model developed, lexical items may be drawn from the lexicon of either language to introduce features into the numeration which must be checked for convergence in the same way as monolingual features must be checked (or must not "mismatch"). The author's proposed Disjunction Theorem further provides that code switching is impossible in the computation N' since the rule ordering (or constraint ranking) associated with the phonological component is not preserved under union (code switching). An extensive discussion shows that the analyses of previous "constraint-oriented" proposals may be derived from the basic feature-checking apparatus of this system. An original corpus ofSpanish-Nahuatl code switching data is additionally presented.The work also discusses applied issues in bilingualism, touching upon assessment, tracking of minority-language students, and notions of bilingual competence and attributed language "deficits." Here the author contends that code switchers are exquisitely sensitive to extremely subtle requirements of both their languages, just as monolinguals are sensitive to theirs. This book will be of interest to scholars in linguistics, bilingualism, and language education.