Using Firenze censuses dated 1841 and 1863 as well as acts of marriages and other Toscany data, the author collected an interesting corpus of domestic servants. She studied and partially published many data about them: ages, employers, marriages. Here is a synthesis of her work. In this article, the author proposes a new approach of the transformations of domestic service in the XIX^th century European urban surroundings, that is trying to interpret its feminization and professionalization while comparing the contrasted situations of Firenze and nearly Prato, with other references to more or less industrialized localities. She underlines growing marginalization and danger of downward social mobility for unemployed domestic servants, men and women. The author could follow specific life courses of women servants who became prostitutes in Firenze thanks to rich Police archives.