While identifying the generic structure of academic introductions has been the focus of extensive research over the last few decades, investigating some, if not all, of the available linguistic resources that realize the identified generic structures seems to have been largely under-focused. In order to shed light on the way that the communicative purposes performed by academic introductions depict themselves in the linguistic choices exploited by language producers, the present study aimed to investigate the thematic organizations that characterize three main variations within the introductory sections of 60 academic textbooks (20 forewords, 20 introductions, 20 prefaces). Two analytical models, namely Halliday's (1994) categorization of theme and McCabe's (1999) specification of thematic progression patterns were incorporated. The qualitative and quantitative analyses of the results indicated that the differences between the three introductory variations in thematic configurations could be attributed to the nature and purposes fulfilled by the genre under investigation. Thus, in order to achieve their intended goals, academic writers need to consider the role played by different theme types as one of the available linguistic resources that help communicate their purposes.