Abstract This article synthesizes the broad impact of Spanish introductions in the New World for the Central Andes (Peru, Ecuador, and Bolivia). Beginning in 1531, the Spaniards brought, from Iberia and Middle America, material elements of their culture which in time were acquired by native people through both imposition and free choice. Plants, animals, and tools were selectively integrated into native agropastoral systems and architectural elements into settlement patterns. Of the screens that filtered the array of Old World rural traits, keeping some out, permitting others to successfully pass and be adopted, the most significant were conditions that the highland environment imposed and competition from existing elements of the already well-developed Andean agricultural complex. Depopulation disrupted the native agroecosystem, and in the restructuring that followed, European goods and practices were adopted along with the indigenous. About a dozen crop introductions became important among peasants out of a total list three times that long, but European domesticated animals contributed most saliently to peasant livelihoods. These Old World biotic contributions juxtaposed with the native elements into a complex that crystallized between 1550–1650. With house types, building materials, and settlement pattern, the two traditions melded. Much of the Central Andes since then has changed relatively little.