The results of theoretical assessment of two stage thrust augmenting ejectors are presented and compared with those of single stage ejectors. The mixing ducts were of constant cross sectional area, the flows at the inlet and exit planes of each stage were assumed to be uniform, and friction effects were ignored. It was found that staging the ejector increases thrust augmentation at all primary jet stagnation pressures, but is more effective in the low pressure range and with high ejector area ratios for any gas combination. With a Hot Rocket-Air combination, the benefit of staging is much less than with an unheated Air-Air combination, and does not appear to be of practical use.