How did merchants build stable commercial relations with strangers, that is, with traders from other ethnic groups, who spoke different languages, and professed different religions? How did they trust each other and monitor their agents’ honesty in spite of the long distance that separated them? A common historiographic explanation points to the supposed strong ethnic cohesion of trading diasporas in order to explain their success in the global economy of the early modern period. In her recent book, Francesca Trivellato challenges this essentialist view. Through the study of the business letters of Ergas & Silvera, a general partnership based in the Tuscan port of Livorno in the first half of the eighteenth century, the author shows the heterogeneity of its trading networks: the Sephardim from Livorno could cooperate with coreligionists as well as with Catholics in Europe and Hindus in Goa, according to the incentives offered by various potential partners. This cooperation, however, did not lead to the dissolution of existing prejudices between the different groups. The book convincingly encourages scholars to compare trading diasporas and displays a successful example of a connected “global history on a small scale”.