Ties Between the Lexicon and Grammar: Cross-Sectional and Longitudinal Studies of Bilingual Toddlers


  • This research was supported by grants to Barbara T. Conboy from the Head Start Research Scholars' Program (Administration on Children and Families), the University of California Linguistic Minority Research Institute, Bamford-Lahey Children's Foundation, and the College of Health and Human Services, San Diego State University. We thank Erik Fritz for help in analyzing the data, and Elizabeth Bates, Rechele Brooks, and Donna Jackson-Maldonado for helpful discussions regarding this work. We are especially indebted to the children and parents who participated in these studies and their parents. These results were previously presented as part of the doctoral dissertation of the first author.

  • Barbara T. Conboy is now at the Institute for Learning and Brain Sciences, University of Washington.

concerning this article should be addressed to Barbara T. Conboy, Institute for Learning and Brain Sciences, University of Washington, Box 357988, Seattle, WA 98195-7988. Electronic mail may be sent to bconboy@u.washington.edu.


Studies using the English and Spanish MacArthur Communicative Development Inventories demonstrated that the grammatical abilities of 20–30-month-old bilingual children were related more strongly to same-language vocabulary development than to broader lexical-conceptual development or maturation. First, proportions of different word types in each language varied with same-language vocabulary size. Second, individual changes in predicate and closed class word proportion scores were linked to growth in same-language vocabulary but not to total conceptual vocabulary. Third, increases in English utterance length and English and Spanish sentence complexity were related to growth in same-language vocabulary but not to growth in conceptual vocabulary. Increases in Spanish utterance length were linked to growth in both Spanish vocabulary and conceptual vocabulary. Possible mechanisms underlying these patterns are considered.