This chapter explores intra-individual variation (IAV) in three nineteenthcentury private letters. Quantitative and qualitative analyses of these letters, written in 1845 by a maid working in Graz (Austria) to her sister in Straden (Austria), illustrate to what extent the language use of the same person can vary in writing. In these letters, variation can be found on all core linguistic levels (on the orthographic-phonetic level as well as on the level of morphology and syntax), with the use of punctuation and lexis also varying. Differences between the three letters as well as variation within them are discussed in detail, showing that they are generally not random. Both language-internal and language- external factors are considered to explain instances of IAV in these letters and to widen our understanding of linguistic variation in nineteenth-century Austria.