The first specialist conference on population balance modelling (PBM) of particulate systems was held in Hawaii in January 2000. Co chaired by Professor Michael Hounslow (The University of Sheffield), Kal Sastry (University of California, Berkeley) and John Herbst (J.A. Herbst and Associates), this conference provided a forum for scientists and engineers to share their ideas on applying, solving or posing population balance models to help understand particulate processes over a range of length scales and applications.