He specializes in the social and economic history of seventeenth-century Peru and is currently researching arbitrismo. He has published in The Americas, Journal of the American Portuguese Society, Hispanic American Historical Review, Anuario de Estudios Americanos, Revista de Indias, Ibero-Amerikanisches Archiv, and Jahrbuch fuer Geschichte von Staat, Wirtschaft und Gesellschaft Lateinamerikas. He won the 1978 Robertson Memorial Prize.