Applied Psycholinguistics 23 (2002), 567-598 Printed in the United States of America 001: 1O.1017.S0142716402004046 Assessing bilingual dominance JAMES EMIL FLEGE University of Alabama at Birmingham IAN R. A. MACKAY University of Ottawa THORSTEN PISKE Kiel University ADDRESS FOR CORRESPONDENCE J. E. Flege, Division of Speech and Hearing Sciences, University of Alabama at Birmingham, CH20, Room 119, 1530 Third Avenue, South, Birmingham, AL 35294-2042. ABSTRACT This study used two methods to assess bilingual dominance in four groups of 18 Italian-English bilinguals, who were selected on the basis of age of arrival (AOA) in Canada (early: 2-13 years; late: 15-26 years) and percentage use of the first language (Ll), Italian (low Ll use: 1-15%; high Ll use: 25-85%). Ratios were derived from the bilinguals' self-ratings of ability to speak and understand Italian compared to English (the "verbal" self-rating ratios) and to read and write Italian compared to English (the "written" self-rating ratios). The ratio of the mean duration of English and Italian sentences produced by each bilingual was also computed. AOA and Ll use had the same effect on the self-rating and sentence duration ratios, which were correlated. The bilinguals who arrived in Canada as young adults and continued to use Italian often were the most likely to be Italian dominant. Dominance in Italian was associated with a relatively high level of performance in Italian (assessed in a translation task) and relatively poor performance in English (assessed by measuring strength of foreign accents). Both groups of late bilinguals (late low, late high) and both groups of early bilinguals (early low, early high) were found to produce English sentences with detectable accents. However, a group of 18 bilinguals (all early bilinguals) selected from the original sample of 72 based on their dominance in English did not have detectable foreign accents. This suggested that interlingual interference effects may not be inevitable. It is common to classify bilinguals as dominant in the first language (L1), domi- nant in their second language (L2), or balanced (i.e., dominant in neither the L 1 nor the L2). A balanced bilingual may be defined as one "who does equally well in both languages" on a variety of tests (Grosjean, 1982, p. 234) or who shows "little interlingual interference" (Lambert, 1990, p. 203). The comparison of homogenous groups of balanced bilinguals differing in age of L2 learning might, therefore, provide a way to choose between two well-known explanations for differences in L2 performance between bilinguals and monolingual native speakers of the L2: the passing of a maturationally defined critical period (e.g., © 2002 Cambridge University Press 0142-7164/02 $9.50