The aim of this thesis is to show how patterns of cohesion and text development differ in English and Arabic, and in doing so add to the growing literature showing that Arabic is still very much an oral language, at least in comparison with English. That is to say, Arabic tends to be written as if to be spoken, whereas English is written as if to be read. The approach taken is quantitative, and stands within the Systemic Functional Model of Grammar, the Textual Component of which has been modified to take into account some of the insights gained by Prague School research into Functional Sentence Perspective. The cohesive analysis, supported by statistical evidence, shows that: 1. Arabic tends to avoid ellipsis. 2. Substitution is a marginal phenomenon in both English and Arabic texts of the type analyzed. However, English tends to use it more than Arabic. 3. The addresser and the addressee are given a higher profile in the Arabic texts than in the English texts. 4. Arabic seems to use a higher proportion of pronouns than English. 5. English displays more use of cohesive synonym items than Arabic. 6. Arabic displays more lexical string repetition than English. 7. Arabic displays more repetition of clause structure than English. 8. Arabic uses more multifunctional connectors than English. In addition the analysis shows that English technical writing favours greater thematic complexity than Arabic does, and different patterns of thematic connection between sentences. In short, the thesis demonstrates that those characteristics which Ong claims are characteristic of an oral language are still present in Arabic to a degree not true of English.