The Old Armenian letters <v> and <w> occur in nearly complementary distribution, but a century of scholarship has failed to resolve whether they denote separate phonemes, allophones, or allographs. The relation of these sounds to the vowel /u/ and interpretation of prevocalic <ow> spellings are also debated. It is argued that Old Armenian had a single phoneme /u/ realized as [u] in syllabic positions, i.e. between consonants or between consonant and word boundary, and [w] or [v] next to a vowel. In initial position the nonsyllabic allophone was realized as [v], including before [ə] < pretonic *i, e.g.vasn[ˈvɑsən] ‘because of, with respect to’,vnas[vəˈnɑs] ‘harm, damage’, underyingly /uasn/, /uinas/. In word‐medial position the realization was [w] or perhaps [ʋ], which was written <v> afteroand <w> after other vowels. After a consonant, <w> occurs in the oblique case forms ofwo‐ andwo/ea‐stems, where it reflects dissimilation in the sequence *‐iyo‐> *‐yo‐> *‐wo‐; otherwise we find <ow> representing [əw], e.g. inlowanam[ləwɑˈnɑm] ‘wash’, gen.anowan[ɑnəˈwɑn] ‘name’, underlyingly /luanam/, /anuan/. The diphthongsaw,ew,iw,ovcan therefore be interpreted as sequences of vowel + /u/, as int‘iw/t‘iu/ ‘number’, gen.t‘owoy/t‘iuoy/.