The distribution of preboundary lengthening within the phrase-final word is controversial. In CV syllables immediately preceding a prosodic boundary, the acoustic duration of the syllable onset C is less involved than that of the following rime V in the lengthening phenomenon. Moreover, preboundary lengthening might be extended to the stressed/accented rime within the phrase final word. On the other hand, articulatory constriction gesture for the onset consonant can be lengthened despite not being immediately adjacent to a boundary. In this study, we explore the effects of prosodic boundary and prominence in Italian, at both acoustic and articulatory level. Bilabial consonants in CV onset position were examined. The consonants were inserted in unstressed (word final) and stressed (penultimate vs. antepenultimate) syllables occurring in the vicinity of prosodic boundaries of different levels. In final syllables, the acoustic duration of the onset consonant was not affected by the prosodic boundary manipulation whereas the closing gesture duration showed a pattern of lengthening which was stronger for higher level prosodic boundaries. In non-final syllables, no acoustic/articulatory effect was found for onset consonants but only on the stressed vowels in penultimate position. Structural, phonological and phonetic constraints might be at work in determining preboundary lengthening.