One of the objectives of English as Lingua Franca (ELF) researchers is an account of the unique features of English that they have found in the speech of European users of English. These features, it is argued, describe a variety of English which they label "English as Lingua Franca". The choice of this particular term is problematic because, as a construct, "lingua franca" generally refers to an overarching function of language, not to any specific set of idiosyncratic forms themselves. However, ELF researchers do not make this distinction. This has resulted in considerable attention being given to a confusing use of linguistic terminology and to the assumptions and theoretical underpinnings guiding ELF research. This paper extends this discussion to an examination of the relationship of ELF studies to English in Europe and the adequacy of "lingua franca" to represent the sociolinguistic realities of world Englishes. It first looks at work written by prominent ELF researchers to determine what they mean by "lingua franca", outlines the distinction between form and function with illustrations of the role and status of English in Europe, and discusses how the architect's principle that "form follows function" is relevant to an understanding of the notion "lingua franca".