Next-to-next-to-leading-order soft-gluon corrections in direct photon production

Previous work on soft-gluon resummation for direct photon production is extended to include additional subleading logarithmic terms through O(alpha alpha_s^3) and some representative comparisons are made to experimental results from the E-706 and UA-6 Collaborations. The additional terms are small in magnitude, indicating good convergence properties to the level of accuracy calculated. The scale dependence remains much smaller than that of the next-to-leading-order calculation.