The compatibility of polyester ionomers with polar polymers (i.e., poly(ethylene terephthalate) and nylon 6,6) is under investigation for their potential use as minor component compatibilizers. Binary blends have been prepared by both solution and melt-mixed methods to determine the effect of melt-processing on blend compatibility. The effect of the sulfonate group and counterion type on compatibility was evaluated by blending sulfonated and nonsulfonated forms of the amorphous polyester ionomer with both nylon 6,6 and poly(ethylene terephthalate). The melting point and phase behavior of the blends were determined by differential scanning calorimetry (DSC) and environmental scanning electron microscopy (ESEM), respectively. A comparison of the melting behavior between the melt and solution blends suggests compatibility due to specific interactions for the ionomer/nylon 6,6 blends. and transesterification for the ionomer/poly(ethylene terephthalate) blends. The phase morphology of the melt blends is consistent with the results obtained by DSC analysis.