This study applies minimum fluidization velocity experiments, X-ray computed tomography (CT), X-ray stereography, and particle tracking to fluidized beds of glass beads, ground walnut shell, and ground corncob operating with a variety of flow conditions. 3-D local, time-averaged gas holdup is calculated from CT data, while dynamic features are captured by X-ray stereography. The results show that CT is most effective on glass bead fluidized beds. Due to high X-ray attenuation, glass bead CT data has higher resolution than walnut shell and corncob beds. Glass bead gas holdup data also feature the lowest noise due to the high homogeneity of the beads. Conversely, stereography is most effective in corncob and walnut shell fluidized beds. High X-ray penetration in these beds allows clear observation of internal flow features. It is also determined that increasing the superficial gas velocity in the bed decreases the effects of side air injection.