Fluid bed granulation is a complex, multi-phase, multi-component unit operation often used in the pharmaceutical industry. Various attributes such as particle morphology, size, porosity, wettability, and binder viscosity play key roles in determining the overall size and composition of the granules that are produced. In this paper, we examine the interaction between binder addition and particle morphology and its impact on granule growth. A multi-dimensional population balance model that tracks the evolution of granule size and binder content distribution is used. A constant-number Monte Carlo algorithm that has been adapted to accommodate continuous processes such as the continuous addition of binder to a system is employed to solve the population balance. Simulation results are then compared with experimental results. (C) 2012 Elsevier B.V. All rights reserved.