An estimation method, which was developed by S. W. Benson and coworkers for calculating the thermodynamic properties of organic compounds in the gas phase, has been extended to the liquid and solid phases for organic compounds at 298.15 K and 101,325 Pa. As with a previous paper dealing with hydrocarbon compounds, comparisons of estimated enthalpies of formation, heat capacities, and entropies with literature values show that extension of the Benson’s group additivity approach to the condensed phase is easy to apply and gives satisfactory agreement. Corresponding values for the entropy of formation, Gibbs energy of formation and natural logarithm of the equilibrium constant for the formation reaction are also calculated provided necessary auxiliary data are available. This work covers 1512 compounds containing the elements: carbon, hydrogen, oxygen, nitrogen, sulfur, and halogens in the gas, liquid, and solid phases. About 1000 references are provided for the literature values which are cited. §