Motivated by the concept of Communicative Language Ability and the eminence of the IELTS exam, this study intended to scrutinize the representation of functional knowledge (FK) and socio-linguistic knowledge (SK) as sub-components of pragmatic knowledge in the writing performances of both tasks of the online General IELTS-practice resources across three band scores. This quantitative inter-scores/intra-tasks and inter-tasks investigation aimed to reveal firstly whether the writers of three band scores 7, 8, and 9 differed from each other in their FK and SK level, and secondly whether the tasks differed in activating them. This study adopted a taxonomy of five illocutionary acts and 20 register features to investigate representation of FK and SK in a well-established corpus of 180 writing performances through both manual analysis and Multidimensional Analysis Tagger software. While the results of statistical analyses revealed no FK differences between the bands in task one (T1), T2’s higher bands involved more functional features because of the expression of a diverse range of psychological states, no speaker’s involvement, and less commitment to a future course of actions. Furthermore, socio-linguistically, band 9 scripts encompassed more logical relations, but conversational and spoken style in T1 and more integration, less simplified structures and ego-involvement in T2. The inter-task analyses uncovered T1’s greater activation of FK through self-mentions, others involvement, emotion, and intention expression. Nevertheless, when it came to SK register features, T2 overdid in both spoken and written genre elements except in persuasion, writers’ involvement, mental acts expression, and interactive discourse creation.
