The densities have been measured at 298.15 K and atmospheric pressure for nine binary mixtures of N-methyl-2-pyrrolidinone with + 2-propanone or + 2-butanone or + 2-pentanone or + 3-pentanone or + cyclopentanone or + 2-hexanone or + 4-methyl-2-pentanone or + 4-heptanone or + 5-nonanone using a vibrating-tube densimeter. The excess molar volumes have been calculated from measured values of densities. The excess molar enthalpies have been measured at 298.15 K and atmospheric pressure for two mixtures of N-methyl-2-pyrrolidinone + 4-heptanone or + 5-nonanone using flow calorimetry. The experimental results have been correlated and compared with the results from the Flory-Benson-Treszczanowicz (FBT) theory and from the extended real associated solution (ERAS) theory. The results are discussed in terms of the intermolecular association.