Recently, there has been a considerable increase in interest in the teaching and assessment of interactional competence. However, its key to ensure that any assessment rubric functions effectively and reliably. This presentation reports on the process of rubric development that combined quantitative analysis using Many Facet Rasch Measurement with qualitative feedback from raters. Based on these analyses, recommendations are given for the development of well-functioning, reliable rubrics for assessing interactional competence and speaking skills.