This book addresses how cross-linguistic interference is represented in the bilingual mind. Examining novel oral production data from older bilingual children representing two Quechua varieties, this research concludes that interference in the feature specification of functional categories leads to language change in a language contact situation, and links convergence, a common set of feature values for the same functional category in both languages to the activation of features related to the informational structure of the sentence. These mechanisms are illustrated in detail by the presence of overt determiners, canonical SVO word order and the absence of accusative marking in bilingual Quechua and by neutralization of case and gender distinctions in direct object pronouns as well as in the emergence of null pronouns with definite antecedents in bilingual Spanish.