Partial molar properties are useful thermodynamic properties because their molar average equals the property itself. In this article, we present a description of partial properties in general, and we show that for many partial properties, partial molar properties being a subset, the property is a molar average of the partial properties. Although partial molar properties remain the most useful, several of the other partial properties could have practical applications. (C) 2009 American Institute of Chemical Engineers AIChE J, 55: 2945-2949, 2009