On the origin and evolution of the contrast between tautosyllabic and heterosyllabic sequences of vocoids in Romance Ioana Chitoran 1 and Jose Ignacio Hualde 2 1 Dartmouth College, USA 2 University of Illinois, Champaign-Urbana, USA ioana.chitoran@dartmouth.edu ; jihualde@uiuc.edu Sequences of rising sonority involving high vocoids, of the ia type, have both tautosyllabic and heterosyllabic sources in Romance: A) In many Romance languages (Spanish, French, Italian, Romanian) Late Latin stressed //, // underwent a process of “breaking”, although under somewhat different conditions in different languages, producing rising diphthongs: Late Lat. p[]tra > Sp. p[je]dra, Fr. p[j]rre, It. p[je]tra, Rom. p[ja]tra. In addition, In Italian and Romanian, the vocalization of /l/ in stop-liquid clusters constitutes another important source of rising diphthongs: Lat. ple na > It. p[je]na ‘full, fem.’; Lat. clamare > Rom. k[je]ma ‘to call’. Other Romance languages (Portuguese, Catalan) did not undergo this diphthongization (e.g., Port. and Cat. pedra ‘stone’). B) At the same time, Latin possessed the relevant sequences, which were heterosyllabic (in hiatus) in the classical language: cliens ‘client’, Italia. In this paper we study four Romance languages, each with a different degree of contrast: Romanian (diphthong-hiatus contrast), Spanish (partial contrast), French (no contrast – all diphthongs), Portuguese (no contrast – all hiatus). We show that the different stages of contrast found in the modern languages are predictable from the presence/absence of the [j] glide in the lexicon from historical sources, along with prosodic effects on the duration of vocalic sequences. In principle, we would expect to find an etymologically-determined lexical contrast between rising diphthongs and hiatus sequences in Romance languages with both A and B. This contrast, however, is only found in Romanian, where ia-type sequences are syllabified as diphthongs when deriving from breaking of mid vowels, as in [pjatr] ‘stone’, [pjerde] ‘lose’, and are heterosyllabic in all other cases, as in [pi.astru] ‘a coin’ (Chitoran 2001, 2003). In Italian and French (at least the standard varieties) a diphthong-hiatus contrast is practically absent. All sequences are syllabified as diphthongs, regardless of etymological origin. Spanish presents a more complex situation. Standard Peninsular Spanish has a partial lexical contrast between diphthong and hiatus. This is because reduction to diphthong of originally heterosyllabic sequences has been blocked under certain conditions: across a morphological boundary as in boqu[i-a]ncho ‘wide-mouthed’ (Navarro Tomás 1977, Hualde 1997), or if the word is paradigmatically related to another word where the high vowel is stressed, as in l[i.á]mos ‘we tie’, cf. l[ía]s ‘you tie’. Moreover, in Spanish we find cases of exceptional hiatus that are not morphologically or paradigmatically justified. This type of exceptional hiatus is subject to two conditions: initiality and stress. Most of these sequences are word-initial and the stress falls either on the second vowel of the sequence or on the next syllable, but not further to the right (Hualde 1999). We show that exceptions occur in these contexts because these are positions where segments tend to be produced with relatively greater duration. This increased duration may have slowed down the phonological recategorization as diphthongs of original heterosyllabic sequences, revealing a change in progress in the case of Spanish (cf. Cabré & Prieto, to appear). We further show that in Romanian, sequences judged as heterosyllabic (those not resulting from the breaking of mid vowels) are in fact highly variable, with greater duration in precisely the same contexts where exceptional hiatus may be found in Spanish. We also examine French and Portuguese, languages without a phonological diphthong-