The article collects ten letters between the Italian statistician, demographer and sociologist Corrado Gini and the American sociologist Robert K. Merton, they exchanged from 1936 till 1940, after a visiting period Gini spent at Harvard University between 1935 and 1936, having the young Merton, at the time PhD student, as teaching assistant. The correspondence is a testimony of the close relationhsip - professional and personal - the two scholars developed in those years, exchanging advices, research suggestions, bibliographic references and publishing opportunities. The correspondence has been transcribed from the original letters, edited and annotated by Marco Santoro.