Ida Altman has written a book that both probes deeply the significance of tying together Iberian and American domains under a common Crown government and brilliantly demonstrates how the comparative history of the first global age ought to be approached. Several recent works have shown the importance of bullion flows, especially those of silver. But for the development of a truly world economy and history, the resulting networks did not have the same impact on all of the localities that they increasingly connected. Altman does an outstanding job of exploring such differences, and their relationship to the interface between the macro-history of the period's new economic and political domains and the micro-history of locality, in ways that highlight human agency.