Measuring language dominance, broadly defined as the relative strength of each of a bilingual’s two languages, remains crucial methodological issue in bilingualism research. While various methods have been proposed, the Bilingual Language Profile (Birdsong et al., 2012) has been one of the most widely used tools for measuring language dominance. While previous studies have begun to establish its validity, the Bilingual Language Profile has yet to be systematically evaluated with respect to reliability. Addressing this methodological gap, the current study examines the reliability of the Bilingual Language Profile, employing a test-retest methodology with a large (N = 248), varied sample of Spanish–English bilinguals. Analysis focuses on the test-retest reliability of the overall dominance score, the dominant and non-dominant global language scores, and the subcomponent scores. Results demonstrate that language dominance score produced by the BLP shows ‘excellent’ levels of test-retest reliability. In addition, while some differences were found between the reliability of global language scores for the dominant and non-dominant languages, and for the different subcomponent scores, all components of the BLP display strong reliability. Taken as a whole, this study provides evidence for the reliability of Bilingual Language Profile as measure of bilingual language dominance.


This is the author-accepted manuscript version of Olson, D. J. (2023). Measuring bilingual language dominance: An examination of the reliability of the Bilingual Language Profile. Language Testing, 1–45. Copyright Sage, the version of record is available at DOI: 10.1177/02655322221139162. Reuse is restricted to NC-ND.


bilingualism, language dominance, proficiency, reliability, questionnaire

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