Various experimental methods have been used to determine the critical pigment volume concentration (CPVC) of coating systems. All of them involve the making of paints formulated over a range of pigment volume concentrations (PVC) and the examination of changes in the film properties. This paper reviews some of these methods. It then goes on to review the development of mathematical models to predict the CPVC and examine some of the factors affecting the measured CPVC in latex paints.