Diving Deep Into the Relationship Between Speech Fluency and Second Language Proficiency: A Meta-Analysis

Abundant research has indicated fluency features as meaningful predictors of second language proficiency. However, the extent to which different fluency dimensions and features can predict proficiency remains underexplored. This meta-analysis employed a multilevel modeling approach to synthesize fluency–proficiency relationships from 71 empirical studies from 1959–2023. Additionally, we examined several moderator variables, including task type, learning context, age, and proficiency measure. The correlations found were strongly positive for speed (r =.55), moderately positive for productivity (r =.38), moderately negative for breakdown (r = −.33), and weakly negative for repair (r = −.11). Moderator analyses revealed that task, learning context, and proficiency measure influence fluency–proficiency relationships in the repair, productivity, and speed dimensions, respectively. Post hoc analyses also suggested that the operationalization of breakdown features might make a difference in fluency–proficiency relationships. This study has both theoretical and methodological implications for second language fluency research.