The monastic orders were preservers and promoters of natural philosophical (and other) learning since late antiquity. But the major new orders of the Middle Ages—Franciscans and Dominicans—developed new natural philosophical outlooks and programs as part of their theology. This lecture looks at these two orders, their origins, their distinctness, and the scientific work of Roger Bacon among the Franciscans and St. Albert the Great among the Dominicans, and others.