No two areas have affected Catholic self-understanding and its relations to other peoples of the world than its approach to Christian mission and to the role of religion and the church in society. Before the Vatican Council (1962–1965), Catholicism was committed to a dominant role to the detriment of other religions and non-believers. Catholic affirmations of freedom and evangelization in matters of religion for all persons creates a whole new context where Catholics predominate, and a whole new set of relations where Catholics participate with others in a pluralist society. How have both non- Catholic societies and the Catholic Church changed over the last forty years because of these two documents? This volume opens a window on these historic developments.