Freezing point depression of milks of various concentrations (i.e. 0-35 wt%) were measured by the thermistor cryoscope method. The method was initially validated using aqueous NaCl and sucrose solutions at high concentrations as their data are readily available in literature. The effect of fat content on freezing point depression of milk was found to be minimal Effective molecular weights were calculated based on existing semi-empirical thermodynamic relationships. The effect of aging of skim milk at high concentrations on freezing point depression was also observed and the quantitative results are reported here.