In this masterful study of the critical issues in missional ecclesiology, Joon-Sik Park reflects on two prominent twentieth-century theologians - H. Richard Niebuhr (1894-1962) and John Howard Yoder (1927-1997) - and integrates the insights of their respective traditions. Although ecclesiology was a major concern to both Niebuhr and Yoder, their views on the nature and calling of the church were distinct. Whereas Niebuhr (a theologian in the Evangelical and Reformed tradition) was concerned with defining the church in relation to a universal community, Yoder (standing within the Mennonite tradition) was interested in representing the church as an alternative community. Although Niebuhr was reluctant to distinguish the church sharply from the world, Yoder stressed the distinctiveness of the church from the world and considered the Christian faith a decisive difference between believing and unbelieving communities. Seeking to construct an integral missional ecclesiology, Joon-Sik Park carefully engages Niebuhr and Yoder and proposes a critical synthesis of their strengths. He holds in creative tension the contradistinctive ecclesiologies of Niebuhr and Yoder by means of Lesslie Newbigin's logic of election, providing a way to overcome an impasse between the two theologians.