Di Felice (1994) has shown that the ratio of the drag coefficient, C-D, on a sphere in a liquid-fluidized bed of uniform spheres to the drag coefficient, C-DS, on the same sphere in isolation and subjected to the same superficial liquid velocity, u, is given by a function epsilon(-beta), where beta was expressed as an empirical function of the particle Reynolds number, Re = du rho/mu. Here it is shown that C-D/C-DS is well approximated by epsilon(-mn), where the Richardson-Zaki index n is a function of the terminal free-settling Reynolds number, Re-t = du(t)rho/mu, and m is 2 plus the slope of the standard log C-DS vs. log Re plot at Re congruent to Re-t. The present model, using the best experimentally confirmed equation for n and a new simple equation for m, is compared with that of Di Felice in their respective abilities to predict liquid-fluidized bed expansion.