Fueling system functions for the International Thermonuclear Engineering Reactor (ITER) and similar scale devices are to provide hydrogenic fuel to maintain the plasma density profile for a specified fusion power, to replace the deuterium-tritium (D-T) ions consumed in the fusion reaction, to establish a density gradient for plasma particle (especially helium ash) flow to the edge, and also to supply hydrogenic edge fueling for increased scrape-off layer flow for optimum divertor operation. An additional function is to inject impurity gases at lower flow rates for divertor plasma radiative cooling, for wall conditioning, and for plasma discharge termination on demand. The burn fraction of ITER is about 1%, which is more than an order of magnitude lower than values typically assumed in fusion reactor studies. This low burn fraction results in large vacuum pumping and fuel processing systems to handle the larger D-T throughput. Gas and pellet fueling efficiency data from past tokamak experiments are reviewed; pellet fueling efficiency is significantly larger than that of gas injection. An overview of the current research and development status of gas and pellet fueling technology is presented.