A thorough experimental description of the time-averaged solids flow in the fully developed region of a cylindrical gas-liquid-solid fluidized bed was provided by using a noninvasive radioactive particle tracking technique (RPT). The 3-D local instantaneous velocity components (radial, axial, azimuthal) of a single radioactive solid tracer, having properties identical to those of the solids in the bed, were measured noninvasively over extended time periods to establish the radial distributions in the fully developed region of axial and radial particle mean and turbulent velocities, shear stress, and axial and radial eddy diffusion coefficients. Glass beads and polyvinyl chloride particles of various shapes and sizes were water-fluidized singly or as binary mixtures in a 100 mm ID Plexiglas column over air and water superficial velocity ranges that spanned the dispersed bubble, coalesced bubble, and transitional flow regimes.