Steady-state permeation measurements are reported for carbon dioxide (CO2) through quenched, amorphous films of a miscible blend of poly(butylene terephthalate) (PBT) and a random copolyester of bisphenol-A and iso/terephthalate acids (PAr). Permeabilities were determined at 35 degrees C on blends with up to 60 wt % PBT and for CO2 pressures up to 300 psi (2.06 MPa). At a fixed blend composition, the permeability, (P) over bar, decays with driving pressure, p, as described by dual-mode models for gas transport in glassy polymers. From regression fits of the data to dual-mode model predictions for (P) over bar(p), high- and low-pressure limiting permeabilities are determined. These decrease with PBT content in a manner indicating strong, favorable energetic interactions between the PBT and PAr components in the blend.