Poly(vinyl alcohol) (PVA) grafted with different hydroxy acids (lactic acid (LA), glycolic acid (GA), and hydroxybutyric acid (HB)) has been blended with poly(vinylpyrrolidone) (PVP) and the miscibility of the g-PVA/PVP blends has been investigated by DSC, FTIR, and molecular modeling. Complete miscibility has been established by DSC for all the systems. The hydrogen-bonded (HB) C=O stretching band of PVP shows a larger red shift than in other polyol/PVP systems. In addition, g-PVA rich blends show a second, highly red-shifted, contribution assigned to double hydrogen bonds. Since this feature is very unusual in polymer blends, the strength of the interactions has been investigated using ab initio QM methods. The interaction energies have been calculated in model compounds for PVA and the polymeric blends at the MP2/cc-pVTZ//MP2/cc-pVDZ level of theory. The infrared spectra of different model compounds and their complexes have also been analyzed. According to the QM analysis, the C=O groups in the pyrrolidone ring and the C=O groups in the hydroxy ester residues adopt antiparallel arrangements establishing attractive dipole dipole interactions. The analysis of the models suggests that the intermolecular interaction between the hyclroxy ester residues in g-PVA and the C=O groups in PVP is stronger than the autoassociation of PVA or g-PVA, providing energetic arguments to explain the occurrence of double HB-s in the condensed phases. The model compounds provide information about the relative strength of the interactions in the polymeric systems.