Isothermal vapor-liquid equilibrium (VLE) and excess enthalpy (HE) data for the two binary systems water + sulfolane and methanol + N-methyl-2-pyrrolidone (NMP) were measured by means of a static technique and an isothermal flow calorimeter, respectively. The experimental data are presented using temperature-dependent interaction parameters for the nonrandom two-liquid model, which were fitted simultaneously to all experimental data from this work and from the literature, and allow us to compare the measured data with the data of the other authors. Furthermore, the experimental results from this work are compared to predictions using the Mod. UNIFAC (Do) group contribution method.