The considerable demographic shift in the use of English worldwide, with the effect that L2 speakers outnumber L1 speakers, particularly as typified in English as a Lingua Franca (ELF) communication, is now widely acknowledged in Applied Linguistics. To a certain extent the resulting impact this has in relation to key issues such as the ownership of English has also been recognised. Description of the linguistic consequences of this shift however is less established, and lingua franca corpora are still in their relatively early stages of development, though growing in momentum. This paper will contribute to the emerging body of work that does report on empirical studies in the field, drawing on two corpora of naturally occurring lingua franca interactions which have been gathered for PhD projects at King's College London. To date reported ELF research projects have tended to focus separately on one or other linguistic system, on phonology (e.g. Jenkins 2000; 2005), and to a lesser extent on pragmatics (e.g. House 1999), and on lexicogrammatical features (cf Seidlhofer 2004). The focus of this paper is to report on findings in both pragmatics and lexicogrammar, and in so doing to identify the interrelationship between the two systems and highlight ways in which they are mutually constitutive. The paper aims to show how pragmatic motives can lead to changes in the lexis and grammar, and in turn how lexicogrammatical innovations impact on pragmatic norms and strategies.