The major findings from Phase I activities in a program entitled Advanced Atmospheric Fluidized-Bed Combustion Design are summarized. It is concluded from these findings that the Ultra High Velocity (UHV) fluidized bed combustion system will meet the criteria established by DOE for an advanced AFBC system. It has the potential for achieving significant technological and economical improvements over the existing AFBC systems. The key technical uncertainties needing resolution before this concept can be considered to have reasonable commercial potential are identified as: operability of the UHV system over the extended turndown range; potential equipment erosion problems anticipated during operation of high gas velocity and solids circulation; and the system performance over the prescribed turndown range to meet the desired performance goals. An R and D program plan to address these issues has been developed, and it is believed that the rick involved in overcoming these technical barriers is well justified by the high payoff potential of the UHV system.