Most handbooks and grammars contend that in Old English the voiced fricatives [v, D, z] were merely allophones of /f, θ, s/ in sonorous environments. How these voiced fricatives became phonemes is debated among scholars. In this article, all previous accounts are critically reviewed. A new proposal is then presented, which explains the facts in a more direct way than previous theses. I argue that phonemicisation of a previous allophonic voice alternation in fricatives had already taken place in many areas of Anglo-Saxon England through language contact with Brittonic. Voiceless as well as voiced fricative phonemes existed in Brittonic at the time of contact, and language shift would have led directly to the phonemicisation of the previous allophonic variation found in early Old English.1 I am grateful to Rolf H. Bremmer Jr, Colin Ewen, Robert Mailhammer, Karling Rottschäfer, Theo Vennemann, David L. White, and the two anonymous referees for useful comments on an earlier draft of this article. 2 There is disagreement about the phonemic status of the contrast of voice in Old English fricatives; I therefore put the fricatives in italics or square brackets '[]' in this introductory section, thus avoiding a phonemic analysis with slants '/ /'. Based on the explanation set out in section 3 of this article, the status of voiced fricatives need not have been the same in all varieties of Old English. 3 The rules in table 1 apply to all Old English dialects with one exception, namely that initial fricatives were voiced in some southerly dialects of Late Old English, and possibly earlier (Fisiak 1984; Dietz 1990: 296-307; Goblirsch 2003 and 2005: 83-101). More copious Middle English evidence shows that initial voiced fricatives were found, very approximately, to the south of a line running from mid Shropshire in the west to the Essex-