A phase diagram is presented for aqueous solutions of oxyethylene/oxypropylene (E/B) block copolymer E(41)B(8). The concentration range covered is 5-70 wt %. The range of techniques used (tube inversion, polarized-light microscopy, rheometry, and differential scanning calorimetry) enabled regions to be assigned to micellar sol, isotropic soft, gel, isotropic cubic gel, and birefringent hexagonal gel. The soft gel is assigned to a fractal network formed from spherical micelles and highly swollen by the water phase.