Disfluencies, such as pauses, filled pauses, and lengthenings, are common in everyday communication of native (L1) speakers.

Research tracking the causes of such L1 disfluencies has mainly focused on intra-individual differences and found that complexity in message, formulation, and articulation will lead to disfluencies. Research tracking the causes of disfluencies in second language (L2) speech, on the other hand, has predominantly focused on inter-individual causes, seeking to answer the question to what extent disfluencies are telling of overall L2 proficiency.

In this presentation, I will propose that in order to fully understand when, how, and why L2 speakers may be disfluent, research should track both inter- and intra-individual differences in L2 speech. I will present research findings from both approaches. Finally, implications for language teaching and testing will be discussed.