A micromechanical model for the analysis of particulate mechanical behaviour is presented. Non-linear effects were introduced in the model by a non-linear elastic description of the matrix and through a modulus degradation routine. The first part of the study used the experimental data from a range of glass bead/HTPB composites to back-calculate model parameters. The results showed that the model gave a good representation of the processes believed to control mechanical behaviour. These processes include partial particle debonding and progressive debonding from the largest to smallest particles throughout the strain history. The second part of the study examined the sensitivity of the model results to small changes in the adjustable input parameters. The residual bond in a debonded particle was found to have a dominating effect on the calculated results. Based on the sensitivity results, "best guess" interaction and debonding parameters were selected to examine the predictive capability of the model. In most cases, the predicted composite stresses were within 10% of the experimental data. Dilatation was usually over-predicted. The results showed that the model was capable of predicting the mechanical behaviour as long as suitable values for critical stress and adhesion energy were available.