The production of neutral pions in p-p collisions has been measured from 346 to 437 Mev. The method was to detect single photons at laboratory angles of 30°, 60°, and 90° from the decay of neutral pions in the reaction p+p-->π0+p+p. Total cross sections which were obtained in this experiment and previous results for proton energies near threshold, have an energy dependence consistent with the phenomenological theory. Additional data were obtained on neutral pion production in proton bombardment of several complex nuclei from Li to Pb. A cross section for bound neutrons was obtained by a comparison of results from H2O and D2O targets.