The thermal behavior of random copolyamides which are used as model polymers with hydrogen bonds has been investigated by differential scanning calorimetry (DSC), x-ray diffraction, and IR spectroscopy. The quenched copolyamides have only halo patterns in their x-ray diffraction photographs. When the sample was kept at the glass transition temperature (20C), no change in x-ray diffraction was observed after the treatment. The free amide band in the infrared spectrum at 3450 cm**-**1, however, was decreased in intensity by keeping the sample at the glass transition temperature. The transition peak height observed in a DSC curve also increased in the same experiment. It is concluded that in the case of the random copolyamide, structures corresponding to a given enthalpy of the glassy state can be related to the number of hydrogen bonds.