Four different approaches to residual entropy (the entropy remaining in crystals comprised of nonsymmetric molecules like CO, N[subscript 2]O, FClO[subscript 3], and H[subscript 2]O as temperatures approach 0 K) are analyzed and a new method of its calculation is developed based on application of the Boltzmann distribution. The inherent connection of all four methods (based on combinatorics, thermodynamics, mixing, or statistical mechanics-probabilities) to one another is shown. They yield the same numerical value of residual entropy when the "frozen-in" energy difference between the possible intermolecular interactions for different molecular arrangements (configurations) is negligible as compared to k[subscript B]T[subscript fusion]. (Contains 2 figures and 4 notes.)