The concept of Theme is regarded as a functional linguistic element that exists in many languages. The main aim of this study is to explore the functions of Theme in Arabic, applying the Systemic Functional Linguistics framework adopted by Downing (1991). Methodologically, several related real examples have been selected from the written discourse of Modern Standard Arabic and then analyzed contextually. The empirical analysis has revealed that (i) Theme can provide different functions, such as Individual, Circumstantial and Subjective and Logical Frameworks for the interpretation of the Theme, and (ii) Theme can interact dynamically with different grammatical functions (e.g. Subject, Object, etc.) and have different pragmatic functions (e.g. Topic, Given and New information). Therefore, the view that makes a necessary link between Theme on the one hand and Noun Phrase, Topic or Given information on the other hand is proven incorrect and empirically invalid. Similar results have been obtained in the context of English (Downing 1991) but not yet for Arabic? This strengthens not only the universality of the concept of Theme but also its functions.