What are the current ideas describing the large scale structure of the universe? How do they relate to the observed facts? This book looks at both the strengths and weaknesses of the current big bang model in explaining certain puzzling data. It arises from an international conference held at the College de France, Paris in June 2004, which brought together many of the world's leading players in cosmology. In addition to presenting individual talks, the proceedings of the resulting discussions are also recorded. Giving a comprehensive coverage of the expanding field of cosmology, this text will be valuable for graduate students and researchers in cosmology and theoretical astrophysics.