The proposed research network will investigate collective scattering of light from cold clouds of atoms in various complementary situations. To these belong photonic bandgaps in optical lattices, magneto-optic traps, atoms within dipole traps, quantum gases in high-finesse ring cavities and Bose-condensates with vortices. These systems provide ideal toy models for a whole class of phenomena occurring in the interaction between light and matter. In particular, they allow to investigate different aspects of collective light scattering which ultimately will lead to a complete understanding of the topic. Questions on the roles of cooperativity and self-organization of the scatterers, disorder and turbulence in the system, quantum effects in the ensembles, multiple scattering and Anderson localization of photons, super- and sub-radiance of the emitted light, and entanglement between light and matter will be addressed by theory and experiment, and new techniques for measuring and analyzing collective light scattering will be developed. Both experimental and theoretical groups located in Europe and Brazil will work together to develop a thorough understanding of how light interacts with a collectivity of atoms.