Abstract The relationship between L2 linguistic skills and the ability to use language for social purposes is still under-explored. While previous research suggests that higher proficiency coincides with better pragmatic and interactional performance, incongruities are also apparent with some low-proficiency learners being able to communicate effectively, and some high-proficiency learners showing pronounced weaknesses in interactional performance. In this study, 150 ESL learners completed a standardized speaking proficiency test, the TOEFL iBT Speaking section, followed by a test of interactional competence consisting of role plays and monologues. Quantitatively, we found a fairly strong correlation between measures of speaking proficiency and interactional ability, but our qualitative analysis showed a more nuanced picture with some interactionally relevant features apparently impacted by speaking proficiency, whereas others were largely independent of it. We discuss implications for the conceptualization of second language ability, language teaching, and language testing.