Until very recently, the usefulness and the pedagogical implications of the study of thematic options and their role in the thematic progression of texts have been in a way terra incognita for most teachers of English as a Second Language. In this respect, this thesis aims at demonstrating the insights of the Theme-Rheme constructs as important cohesive textual resources at discourse level. By applying this Systemic-Functional approach to the traditional fundamentals of composition writing, both teachers and students can acquire an important text linguistic asset to the evaluation and improvement of ESL writing. The study of thematic options can provide teachers with valuable information on the level of writing effectiveness according to both the type of genre required and what is usually expected in anglophone conventions. Furthermore, it could easily reveal potential influence of first languages over ESL written discourse that, otherwise, would be unnoticed by only focusing on the grammatical clarity of sentences and the conventional textual techniques English language centers usually apply. To address this issue, we have analyzed in terms of thematic options, thematic progression and information structure 40 argumentative essays written by four different groups of ESL students whose first languages are Spanish, Chinese, Korean and Japanese. This multi-faceted study has also been compared to the analysis of a fifth corpus of 10 argumentative essays written by native speakers of American English. As regards the use of thematic structures for denoting markedness as the first constituency of the message, we have found that ESL students and native speakers do differ significantly. We have learned that the first ones have employed thematic prominence mainly as a textual tool for creating time demarcation; a contrasting feature to that of the native speakers who have resorted to the use of marked themes not only for signaling time demarcation but also other types of markedness. There have also been interesting contrasting features with respect to the use of interpersonal Themes among ESL groups that seem to be brought into the English language from their first languages. What usually constitutes the method of development of the text determines what the essay is about, that is, the referential anchoring in Theme position that puts forward the whole thing. It is precisely here that the gap between ESL students and native speakers begins to widen more considerably. The contrastive study of thematic progression in the five corpora has shown even more marked differences than in previous areas analyzed when it comes to the preferred options adopted in the elaboration of the MOD of the texts. For the most part, ESL students seem not to have a pre-determined pattern of thematic development. Some groups overuse constant thematic progression patterns. Native speakers, on the other hand, show a frequent use of cross-referential pattering; a type of TP typically attributed to argumentative texts. However, another interesting finding has been the infrequent use of textual Themes (with internal function) denoting ordering in the presentation of argument sequences among native speakers. In this connection, we have demonstrated that the method ESL students usually employ to organize the blocks or structures of information in their texts conforms pretty much to what is suggested in the corresponding literature.