The miscibility behavior and specific interaction of phenolic/polystyrene-co-acetoxystyrene, (PS-co-PAS) blends by varying acetoxystyrene contents of the PS-co-PAS copolymer were investigated by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR). A miscibility window was found when the acetoxystyrene fraction in the copolymer is higher than 45 mol% in phenolic/PS-co-PAS = 50/50 blend system. Painter-Coleman Association Model (PCAM) is able to predict the miscibility window at 150 degreesC compared with our experimental results based on DSC analyses.