What the Kingdom of God requires is a radical Christian movement in our own time which has a vigor and depth that equals that of those radicals who have gone before us. These words introduce a Radical Reformation Reader, first published in 1971 by a group confident that the past could–and did–offer practical, theological guidance for following Jesus in the contemporary world. What forms of church are appropriate to the ecclesial heirs of such a radical tradition, especially in settings marked by individualism, escalating violence, and growing economic disparity? The essays republished here explore divergent contextual responses and invite readers to do the same.