This article takes a fresh look at merchant networks that linked Spain and colonial Peru in the central decades of the eighteenth century. Spain's trade with its American colonies has been studied primarily in the light of mercantilistic policies design to revive the exchanges. Much attention has been paid to the fierce rivalry between the merchant guilds of both sides of the Atlantic (those of Cádiz, Mexico City, and Lima), and their efforts to exert control over the trade, suggesting that transoceanic networks had a minor impact. In contrast, this article stresses the role of collaboration and mutual understanding between American and Iberian merchants. The adoption of a direct route linking Cádiz and Lima via Cape Horn in the 1740s, and the subsequent rise of a new, more competitive pattern of trade compelled merchants to build up sustained transatlantic networks that required a high level of personal trust. By using a previously unstudied cache of confiscated letters, this article shows that transatlantic travel, friendship, common regional and ethnic origin, and the increasing flow of information played a far more important part in the articulation of Spanish colonial trade than any merchant guild rivalry. These networks helped bring both sides of the Atlantic closer than they had ever been.