Assessment of second language fluency

Investigating speech fluency has, for a long time, been at the core of second language (L2) studies, as fluency is believed to epitomise successful acquisition of L2, characterise effective communication, elucidate the complex process of acquisition, and predict L2 speakers' proficiency. The significance attributed to fluency in these areas explicates the research attention paid to it over the past decades. An important area of development in this regard is L2 assessment in which fluency is recognised as a key underlying construct of spoken language ability by international language tests (e.g., IELTS, TEEP, APTIS) and language benchmarks (e.g., CEFR). Many high-stakes tests of English and other languages include fluency in their rating scales, with the earliest on record tracing back to the 1930s – the College Board's English Competence Examination (1930) in America. Including fluency as a fundamental aspect of speaking ability in the rating scales, rating descriptors, and rater training materials, either as an independent criterion or combined with others (e.g., delivery), has become common practice in language testing over the past decades. What has made assessment of fluency even more appealing to researchers and test providers in recent years is the objectivity and reliability of its measurement and its compatibility with the technological developments in automated assessment of speaking. Fluency is now largely recognised as a construct that can be efficiently and reliably assessed in automated assessment of spoken language ability and used to predict proficiency (de Jong, 2018*; Ginther et al., 2010*; Kang & Johnson, 2021*; Tavakoli et al., 2023).