Lexical stress may be signalled through a large number of acoustic parameters. In Italian, stress is realized through (1) longer duration, (2) more peripheral acoustic vowel shape, and (3) higher intensity. Moreover, duration has been shown to be sensitive to the position where stress occurs in the word: penultimate stressed syllables are longer than antepenultimate stressed syllables. Little is known however on other acoustic correlates and on articulatory correlates of this positional effect. Using EMA (AG501), we aim to investigate and to describe the interplay between the acoustic and articulatory parameters of this positional effect. The results show that (i) antepenul-timate stressed vowels are shorter than penultimate ones, (ii) antepenultimate and penultimate stressed vowels show a com-parable hyperarticulated pattern in tongue dorsum position and formant structure, (3) while antepenultimate stress’ intensity in-creases in accordance with lip aperture, the penultimate stress’ intensity peak occurs at the beginning of the vowel and is fol-lowed by a slope. This is not in accordance with the pattern of lip aperture. The findings are discussed within the hyperartic-ulation and the sonority expansion theories of prominence, and also within the framework of Articulatory Phonology.