At first, no single activity defined the new religious order. The early Jesuits preached in the streets, led men and women through the Spiritual Exercises, taught theology in universities, instructed children in the catechism, and cared for plague victims and prostitutes. Others went off to work in distant parts of the world, as Francis Xavier did in India. They were discovering their mission by doing it, adapting to change, taking risks, and learning by trial and error.

Nonetheless, the early companions were all graduates of the best university of Europe and they thought of themselves as specialists in "ministries of the word." Gradually, they came to realize that there was one emerging activity that connected their intellectual training, their world-affirming spirituality, their pastoral experience, and their goal of helping souls. When citizens of Messina asked Ignatius to open a school for their sons, he seems to have decided that schools could be a powerful means of forming the minds and hearts of those, who, because they would be important citizens in their communities, could influence many others. When the college in Messina proved a success, requests to open schools in other cities multiplied and soon education became the characteristic activity of Jesuits.

When Ignatius died in 1556 there were 35 Jesuit colleges across Europe. Two hundred years later, there were more than 800 in Europe, Asia, and Latin America. They constituted the largest system of education before the modern era of public schooling and the first truly international one.