This paper explores the culture of skilled practice in late sixteenth-century Rome. It takes specific examples of engineers, architects, printers, engravers, and painters to show the ways in which individuals in this time and place led particularly fluid work lives – moving from different kinds of skilled occupations as a way of moving up the social ladder. At the same time, skilled individuals and learned humanists often communicated in substantial ways and even developed friendships in arenas that I have called trading zones. This paper discusses the implications of this fluidity of occupation and the development of trading zones in early modern Europe. The examples are taken from Rome, but it is suggested that although Rome was in some ways unique, these conditions also prevailed in many other places in Europe.