Solutions of block copolymers in selective solvents exhibit a rich variety of structures, both intramicellar (spheres, disks, worms, vesicles…) and intermicellar (fcc, hcp, bcc, A15, AB13,…). The choice of structure may be dictated by a host of variables, including block molecular weights, concentration, choice of solvent, temperature, blending, and addition of homopolymers. In this talk we will describe three illustrative examples, involving (i) the control of micelle morphology by temperature, (ii) the disruption of ordered phases by addition of homopolymer, and (iii) the formation of superlattices by mixing two different micelle populations. Scattering techniques (X-ray, neutron, and light) play the crucial role in quantifying these phenomena.