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Properties of Dual Language Exposure That Influence 2-Year-Olds’ Bilingual Proficiency


  • Portions of this work were submitted by the first author in partial fulfillment of the requirements for the degree of Master of Arts at Florida Atlantic University. This research was supported by grants from the Eunice Kennedy Shriver National Institute of Child Health and Human Development (HD054427 to Erika Hoff and HD054427-S1 to Melissa Señor). We thank Annick De Houwer for translating the language diary from Dutch to English for this project, and we thank Annick De Houwer and Cynthia Core for their helpful comments on this work.

concerning this article should be addressed to Erika Hoff, Department of Psychology, Florida Atlantic University, Davie, FL 33314. Electronic mail may be sent to


The mothers of 29 Spanish English bilingual 25-month-olds kept diary records of their children’s dual language exposure and provided information on their children’s English and Spanish language development using the MacArthur–Bates inventories. Relative amount of exposure predicted language outcomes in English and Spanish. In addition, the number of different speakers from whom the children heard English and the percent of their English input that was provided by native speakers were unique sources of variance in children’s English skills. These properties of children’s dual language exposure and their bilingual proficiency varied as a function of whether the children’s mother, father, or both parents were native Spanish speakers. Practical and theoretical implications are discussed.