Particle radiation therapy has the potential for immediate and sustained favorable impact on management of the cancer patient by providing better local tumor control. Scientific knowledge and expertise are immediately available to mount effective clinical studies of fast neurons, protons, and helium ions, and to initiate necessary preliminary studies of pimesons and heavy ions. Meaningful studies will require a long-term commitment of support. The amount of support, although substantial, is not disproportionate to the potential benefit or existing support of other cancer research programs.