As part of a study of large p/sub T/ phenomena in proton-proton collisions at the CERN ISR, a search for direct single photon production has been performed. A statistical division of the data sample into the fraction consistent with single photon production and the fraction due to multiphoton decays of neutral hadrons is accomplished by measuring the average conversion probability for the sample in a one radiation length thick converter. The fraction of the sample attributable to direct single photon production is .gamma./all = 0.074 +- 0.012 for 6 GeV/c = 0.26 +- 0.04 for p/sub T/> 10 GeV/c, with an additional systematic uncertainty of +- 0.05 for both values. It is found that single photons are produced preferentially with no accompanying particles on the same side. The ratio of positive to negative particles on the away side is found to be 3.7 +- 1.2 at high x/sub E/ and p/sub T/ for the single photon events.