In this report, the phenomenon of vowel lengthening in Standard Italian and two Northern Italian dialects, Friulian and Milanese, is discussed. For each language, the facts of vowel lengthening are presented and analyzed in the framework of several theories previously proposed to account for the data. These include primarily derivational theory, moraic theory, and optimality theory. Vowel lengthening is analyzed predominantly from a synchronic perspective for Standard Italian, but for Friulian and Milanese, both diachronic and synchronic accounts are presented. Vowel length in Italian and Milanese is seen to result from bimoraic enforcement, a principle requiring that all stressed syllables be bimoraic. A constraint prohibiting long vowels in word-final position interacts with the principle of bimoraic enforcement in Italian. In Milanese, bimoraic enforcement responds to a lexical contrast in moraic and non-moraic codas. Vowels before non-moraic codas lengthen to create a bimoraic syllable, while those before moraic codas do not since those syllables are already bimoraic. In Friulian, on the other hand, historical vowel lengthening which resulted from compensatory lengthening following the apocope of final vowels has been reanalyzed as a synchronic process of compensatory lengthening resulting from loss of consonant voice following word-final devoicing. / text