This book explores the cognitive and communicative processes involved in the use of English as a Lingua Franca ELF within crosscultural specialized contexts where nonnative speakers of English i.e. Western experts and nonWestern migrants interact. The book argues that the main communicative difficulties in such contexts are due precisely to the use of ELF since it develops from the nonnative speakers transfer of their native language structures and sociocultural schemata into the English they speak. Transfer in fact allows nonnative speakers to appropriate or authenticate those English semantic syntactic pragmatic and specializeddiscourse structures that are linguistically and conceptually unavailable to them. It follows that there are as many ELF varieties as there are communities of nonnative speakers authenticating English. The research questions justifying the ethnographic case studies detailed in this book are What kind of cognitive frames and communicative strategies do Western experts activate in order to convey their culturallymarked knowledge of specialized discourse by using their ELF varieties to nonWesterners with different linguistic and sociocultural backgrounds What kind of power asymmetries can be identified when nonWesterners try to communicate their own knowledge by using their respective ELF varieties Is it possible to ultimately develop a mode of ELF specialized communication that can be shared by both Western experts and nonWestern migrants