A recent statistical thermodynamic theory of fluids interacting with strong specific intermolecular and intramolecular forces is extended in order to correlate and predict the glass transition temperatures in polymer mixtures. The Gibbs-DiMarzio approach of zero configurational entropy at the glass transition is adopted. The configurational entropy is composed of three distinct parts : a chain flexibility or internal part, an equation-of-state part and a hydrogen bonding part. The approach is tested against our own experimental data and literature data. The agreement between experimental and predicted glass transition temperatures is satisfactory.