This article investigates the central role of topic in the IELTS Speaking Test (IST). Topic has developed a dual personality in this interactional setting: topic-as-script is the scripted statement of topic on the examiner's cards prior to the interaction, whereas topic-as-action is how topic is developed by the candidate during the course of the interaction, which is consequential for the grades they receive. The key interactional structure in the IST is the 'topic-scripted Question--Answer adjacency pair' produced by the examiner. In order to obtain a high score, candidates need to do the following: (a) understand the question they have been asked; (b) provide an answer to the question; (c) identify the topic inherent in the question; and (d) develop the topic inherent in the question. Comparing the two personalities of topic enables methodological analysis and evaluation of the interaction and can be used for preparing candidates for the IST.