The purpose of this introductory chapter is to provide the reader with an overview of the theological discipline of ecclesiology and a basic orientation to its questions and methods. Noting the boost that ecclesiology received from Karl Barth’s Church Dogmatics, Vatican II, and the Ecumenical Movement, the chapter proceeds to explain the etymology of ‘ecclesiology’ and then to define it as the discipline that is concerned with comparative, critical, and constructive reflection on the dominant paradigms of the identity of the church. It then mentions the primary sources of ecclesiology and charts its late arrival on the theological scene. It explores why ecclesiology is inherently problematic—because the church is a divine mystery. Recent developments within ecclesiology are introduced: missiological, ecumenical, feminist, practical, and ethnographical. Four questions to wrestle with are briefly discussed and the chapter ends by raising the possibility of ecclesiology as a vocation.