Investigates the universal categories 'subject', 'theme', and 'agent' with special reference to their functional status in Modern Standard Arabic (MSA) and how these three distinct functions may or may not coincide in Arabic sentences. These functions are inexplicitly characterised by classical and modern Arab linguists and Arabists alike. It has been found that the pre- (viz. sentence - initial) or post-verbal noun phrase (NP) in Arabic can be assigned the syntactic function 'subject' but may not necessarily assume the semantic function 'agent', that the pre-verbal NP, which may not necessarily be the 'subject', has the pragmatic function 'theme', and that these distinct functions sometimes cluster around a single NP in certain sentences, depending on genre. It has also been found that in MSA the order of sentence constituents is relatively free, subject to a verb-initial preference, especially when needed to prevent ambiguity. The present study reveals the fact that although coding features such as word order, case marking, and cross-referencing (viz. agreement) may provide a clear indication of which NPs are 'subjects' in MSA, they do not provide a clear-cut indication of semantic relations such as 'agent'; the 'subject' position in MSA is not necessarily the canonical 'agent' position.