There is today a dramatic reexamination of structure, authority, dogma -- indeed, every aspect of the life of the Church is held up to scrutiny. Welcoming this as a sign of vitality, Avery Dulles has carefully studied the writings of contemporary Protestant and Catholic ecclesiologists and sifted out six major approaches, or "models," through which the Church's character can be understood: as Institution, Mystical Communion, Sacrament, Herald, Servant, and, in a recent addition to the book, as Community of Disciples. A balanced theology, he concludes, must incorporate the major...