The Tanzanian ethnic community language Kagulu is in extended language contact with the national language Swahili and other neighbouring community languages. The effects of contact are seen in vocabulary and structure, leading to a high degree of linguistic variation and to the development of distinct varieties of ‘pure’ and ‘mixed’ Kagulu. A comprehensive documentation of the language needs to take this variation into account and to provide a description of the different varieties and their interaction. The paper illustrates this point by charting the development of a specific text within a language documentation project. A comparison of three versions of the text – a recorded oral story, a transcribed version of it and a further, edited version in which features of pure Kagulu are edited in – shows the dynamics of how the different versions of the text interact and provides a detailed picture of linguistic variation and of speakers’ use and exploitation of it. We show that all versions of the text are valid, ‘authentic’ representations of their own linguistic reality, and how all three of them, and the processes of their genesis, are an integral part of a comprehensive documentation of Kagulu and its linguistic ecology.National Foreign Language Resource Cente