Knowledge of the particle size distribution of a powder is required for various powder technology applications. This particle size distribution is a function of both the method of production of the particulate system and the method measurement of particle diameter. In order for the real particle size distribution of a powder to be determined, one has to disaggregate the powder to obtain the 'initial' size spectrum and an approach to evaluate this has been developed. This is illustrated with examples of powders with both weak and strong interparticle forces. Powders with weak bonds can easily achieve their 'initial' size spectrum, but powders with strong bonds could not, in some cases, be dispersed to the initial state.