Speakers of Persian, like speakers of other languages, utilise Routine Politeness Formulae (RPF) to negotiate central interpersonal interactions. RPF in Persian have not received any systematic description as to their forms, their functions, their typical conditions of use and their discourse structure rules. Bridging this gap, for the first time, RPF from five frequently-used speech acts – namely, greeting, leave-taking, apologizing, thanking and requesting – are documented in this thesis. Data were derived from Persian soap operas and from role-plays with native speakers, and were entered into a database for further analysis. The analysis is qualitative and the data are conceived of as phraseological units to be represented as dictionary entries. The study of the aforementioned speech acts and their related array of RPF reveals the dynamics of interpersonal polite behaviour among Persians, reflecting the following socio-cultural values prevalent in Iranian society: (i) its group-oriented nature, (ii) a tendency towards positive (solidarity) politeness, (iii) sensitivity to remaining in people’s debt, (iv) sensitivity to giving trouble to others, (v) a high premium on reciprocity in interpersonal communications, (vi) the importance of seniority in terms of age and social status, and (vii) differentiation between members of the ‘inner circle’ and the ‘outer circle’. This thesis also reveals the dominance of the strategy of self-lowering and other-elevating. Almost all RPF in Persian allow for the use of this pervasive strategy, which is also manifested by two further sub-strategies: (i) a propensity to exaggerate favours received from others, and (ii) giving precedence to others over oneself. Finally, it is suggested that Islamic teachings have significantly influenced the formation and use of certain RPF. The dictionary resulting from this work can serve as a resource for researchers in sociolinguistics and pragmatics, and for the teaching of Persian to non-Persian speakers.