Recent experiments have shown that thermodynamically stable, bicontinuous microemulsions can be achieved in symmetric ternary blends of 2 homopolymers and the corresponding diblock copolymer. These blends can generate swelling of the preexisting morphology, phase separate, or form microemulsions depending on the composition. Increasing the homopolymer volume fraction generates the formation of microemulsions, fluids which are microscopically segregated and macroscopically disordered.