Coexistence curves for binary polymer/solvent solutions are asymmetric when volume fraction is used as the concentration variable. Coexistence curves for polystyrene/methylcyclohexane solutions can be symmetrized by a simple transformation of variables; in the new dimensionless variable &psgr;, all of the data satisfy a universal scaling law: ‖&psgr;−&psgr;c‖=&psgr;0(&egr;N0.313)&bgr;; &egr;≡(Tc−T)/Tc, whereNis the degree of polymerization and &psgr;cand &psgr;0are constants independent ofN. The experimental value of the critical exponent &bgr; (0.327±0.002) agrees well with recent renormalization group calculations for the Ising model. The exponent onN(0.102±0.002) may be universal and should be compared with its mean‐field value of 1/4; a calculation of its nonclassical value remains a challenging theoretical problem.