“Hablamos los dos. We speak both (p. 1).” A statement offered by a 9-year-old girl defines the principle assertion of this book: Bilinguals have available to them at least two distinct repertoires of language that they are able to manipulate and mix to achieve their unique discourse needs and to express their multicultural identities. This book explores the network of relationships of 20 Puerto Rican families in a low-income neighborhood called el bloque in New York City. Zentella, herself a Nuyorican (New York Puerto Rican), has provided us a window on a world as only an insider can. She follows the families in and out of el bloque for 13 years, monitoring their bilingual behavior and the sociolinguistic factors that contribute to maintenance or loss of bilingual ability.