Using a tailorable poly(styrene-block-glycidyl methacrylate-blockmethyl methacrylate) (PS-b-PGMA-b-PMMA) triblock terpolymer, the effect of changing the Flory -Huggins interaction parameters (chi) on the bulk self-assembly behavior of 12 linear ABC triblock terpolymers was investigated. By introducing different thiols to the short, reactive PGMA middle block, the experimental chi(AB) and chi(BC) could be arbitrarily altered, thereby changing the self-assembled morphologies that were characterized by small -angle X-ray scattering and transmission electron microscopy. Observed morphologies included lamellae, hexagonal cylinders, and tetragonal cylinders, which were found to be in close agreement with the expected morphologies obtained by self-consistent field theory simulation. Extending the 12 experimental results, 400 simulations were carried out to construct the chi(AB)-chi(Bc) phase diagrams of the terpolymer at four different degrees of polymerization. The experimental and simulation results demonstrated that both the magnitude and the relation among each of the three interaction parameters are vital in determining the self-assembled morphology.