Electric fields have been shown to stabilize the disordered phase of near-critical block copolymer solutions. Here, we use in situ synchrotron small-angle X-ray scattering to examine how the initial orientation of lamellar domains with respect to the external field (φ) affects the shift in the order-disorder transition temperature (TODT) of lyotropic solutions of poly(styrene-b-isoprene) in toluene. We find a downward shift of the transition temperature, which scales with lamellar orientation as ΔTODT ∼ cos2 φ, in accordance with theory.