Two physical processes for producing chemically and physically distinct fractions from milk fat were investigated. In both cases, separation is due to differences in phase behavior between the many components in milk fat. Short-path distillation separated components due to differences in their partial pressures. For a complex system like milk fat, the percent of total mass in the distillate (PMD) was found to be the best variable for predicting the composition of resulting fractions. The number average molecular weight (MWN) was a good indicator of separation efficiency. Dry and solvent fractionation processes are crystallization based separation technologies. A mechanism for fat crystallization was proposed and used to illustrate aspects of milk fat crystallization behavior. Differences in crystallization and melting behavior between seeded (with [alpha] and [beta]' polymorphs) and unseeded milk fat were studied in DSC temperature cycling experiments. Dissolution and cocrystallization due to added solvent was investigated.