This article on interactional competence provides an overview of the historical influences that have shaped theoretical conceptualisations of this construct as it relates to spoken language use, leading to the current view of it as involving both cognitive and social dimensions, and then describes its operationalisation in tests and assessment scales, and the challenges associated with this activity. Looking into the future, issues that need to be dealt with include developing a fuller representation of the construct and of more contextually relevant assessments, deciding upon additional assessment criteria and the appropriate interpretation thereof, and determining how technology can be applied in assessment practice and the extent to which technology fundamentally changes the construct itself. These all have implications for testing if it is to be relevant and fit for purpose.