The multidimensional nature of American Catholicism requires attention to mission and evangelization as one lens through which to understand the global dynamics of the American Catholic experience. Evangelization and mission were more nuanced than simply “converting” or “civilizing” people. Mission encounters in diverse local contexts transformed those on both sides of the relationship. This chapter will explore briefly three themes: mission to America (“transplanting,” or handing on the faith); the growth of an evangelization/mission impetus within the United States; and the effect of mission engagement from the United States. These mission encounters involved much more than simply learning a catechism. Missionaries effected social change, religious development, and humanitarian responses to injustice in many countries, even while at times carrying on practices that sometimes had a negative effect on the people they came to serve.