Journal of Child Language

A crosslinguistic study of the relationship between grammar and lexical development 1

a1 University of Rome ‘La Sapienza’
a2 Institute for Cognitive Science & Technology, National Council of Research, Rome, Italy
a3 University of Rome ‘La Sapienza’
a4 Fatebenefratelli Hospital, Rome, Italy
a5 San Diego State University
a6 University of California, San Diego

Article author query
devescovi a   [PubMed][Google Scholar] 
caselli mc   [PubMed][Google Scholar] 
marchione d   [PubMed][Google Scholar] 
pasqualetti p   [PubMed][Google Scholar] 
reilly j   [PubMed][Google Scholar] 
bates e   [PubMed][Google Scholar] 


The relationship between grammatical and lexical development was compared in 233 English and 233 Italian children aged between 1;6 and 2;6, matched for age, gender, and vocabulary size on the MacArthur Communicative Development Inventories (CDI). Four different measures of Mean Length of Utterance were applied to the three longest utterances reported by parents, and to corrected/expanded versions representing the ‘target’ for each utterance. Italians had longer MLUs on most measures, but the ratio of actual to target MLUs did not differ between languages. Age and vocabulary both contributed significant variance to MLU, but the contribution of vocabulary was much larger, suggesting that vocabulary size may provide a better basis for crosslinguistic comparisons of grammatical development. The relationship between MLU and vocabulary size was non-linear in English but linear in Italian, suggesting that grammar ‘gets off the ground’ earlier in a richly inflected language. A possible mechanism to account for this difference is discussed.

(Published Online December 13 2005)
(Received July 22 2003)
(Revised January 31 2005)

c1 Department of Development and Socialization Processes, University of Rome ‘La Sapienza’, Via dei Marsi 78, Rome, Italy. tel: 3906-49917655; fax: 3906-4917652; e-mail:


1 This project was partially supported by three grants to Elizabeth Bates: ‘Crosslinguistic studies of aphasia’ (NIH/NIDCD R01-DC00216), ‘Center for the Study of the Neurological Bases of Language & Learning’ (NIH/NINDS P50-NS22343), ‘Origins of Communication Disorders’ (NIH/NIDCD P50-DC01289), and by the National Council of Research Institute of Psychology. We will always remember and treasure Elizabeth Bates, our beloved and admired friend and colleague, and valuable coauthor, who passed away in December 2003, when the manuscript had been submitted but before it was revised.