Rather than reiterate the empirical results and practical reflections found in this literature, my focus here will be on the second question, with special attention to the significant theological challenges that emerging churches raise for ecclesiology and the self-understanding of the nature and task of the Christian church. While much of the debate has been over the validity and value of emerging churches, which are growing rapidly across traditional denominational boundaries and contesting old organizational structures, relatively little attention has been paid to the way in which they challenge the very idea of what it means to be (or become) church.