This thesis discusses the function and perception of the Venetian (or Venetan) tongue from a sociolinguistic diachronic perspective.   Venetian, spoken by over 6 million people in 7 countries, in an Italian context is referred to as an Italian dialect. Though defined as language in Brazil, by the Veneto region in Italy and by several international organizations (amongst them UN and UNESCO), the Italian State does not confirm its status.   Venetian appeared as a written language in the XII century, anticipating the earliest texts in Italian itself in the Florentine form. From the ninth century it was spread by Venetian merchants and by the Venetian Republic itself to the eastern coast of the Adriatic Sea, from Istria down to modern day Albania, and later on even further, to the Greek archipelagos and the ports of the Holy land. The expansion of the "Serenissima" in the Italian hinterland led to the homogenisation of the language in the area that forms the base of the modern "Veneto" spoken today.   Venetian was the spoken language in all contexts in the Republic, and was used in official acts, such as the Statuti Veneti, the Mariegole and within the diplomacy. Though the official use of written Venetian was gradually out conquered by Italian from the sixteenth century, it remained the sole spoken language in all state organs until the fall of the Republic in 1797 and was used by the diplomacy of the Ottoman Empire in its contacts with European countries.    After the annexation of Veneto to Italy in 1866, the Italian State has actively combated the use of Venetian (and even forbidden it during the fascist regime), but nevertheless, today Venetian is one the most vigorous of the Italian "dialects": at least 72% of the inhabitants in the Veneto region use the language actively and a recent study demonstrates that as many as 65% of the foreigners living in the region learn the language because of professional or social necessity.   In a diachronic perspective the Venetian tongue can hardly be considered an Italian dialect, not only because of its autonomous development from Vulgar Latin or its different grammar and morphosyntax, but also because of its function and perception: used as an official language not only by the Serenissima, but also by other states, and because of its literacy that for centuries has invented and followed autonomous traditions and created notable works in poetry, theatre, prose and science.