The main objective of this paper is to consider random pseudo-turbulent particle velocity fluctuations in a homogeneous fluidized bed (or in the dense phase of an inhomogeneous fluidized bed). As shown previously, these fluctuations are caused when the relative fluid flow interacts with random fluctuations of particle concentration. Bed particles are assumed to exchange their fluctuation energy and momentum through direct collisions. This being the case, and if particle concentration is sufficiently high, the particle velocity fluctuations are likely to be nearly isotropic, and so they can be characterized by a single scalar parameter. We introduce the doubled mean energy that is related to one translational degree of particle freedom in the capacity of just such a scalar parameter, and ii plays substantially the same role as temperature plays in molecular gases. However, in contrast to temperature. this energy cannot be regarded as an independent variable, but rather represents a function of mean particle concentration and of physical parameters. We then formulate the equation of stale which describes the particulate pressure that is caused by particle velocity fluctuations and is influenced by the conductivity of momentum during collisions. Thus defined, this pressure is successfully employed (1) to model the particle distribution that establishes itself to the fore of a bubble rising in a macroscopically uniform fluidized bed, and (2) to study the hydrodynamic stability of gas-fluidized beds with respect to infinitesimal one-dimensional disturbances.