The Italian migration to the United States spurred a particularly dynamic and multifarious language contact between Italian varieties and American English, which is the main object of study of this monograph. The Italian-American linguistic contact is characterized by a duration of more than 400 years, a wide geographic diffusion and a variable intensity. The author undertakes a diachronic variational analysis of its dynamics and results and provides a methodological innovation for contact studies. Foreword by Tullio De Mauro.