Interparticle forces are important to the particle pressure. Existent models usually adopt the coefficient of restitution to account for the interactions among particles without necessary distinctions in physics. A model is established herein to account for the effect of interparticle forces by using the concept of the Boltzmann distribution with consideration of many-body influences. The predicted particle pressure is compared with reported data in the literature and used to explain stability phenomena in fluidized systems.