Introduction and Theoretical Background -- The LHC and the ATLAS Detector -- Data Samples and Event Selection -- Reconstruction and Identification of Prompt Photons -- Efficiency Measurements -- Background Estimation -- Measurement and Systematics -- Results of the Measurement and Comparison with Predictions -- Extending the Measurement.

This thesis reports on the first studies of Standard Model photon production at the Large Hadron Collider (LHC) using the ATLAS detector.  Standard Model photon production is a large background in the search for Higgs bosons decaying into photon pairs, and is thus critical to understand.  The thesis explains the techniques used to reconstruct and identify photon candidates using the ATLAS detector, and describes a measurement of the production cross section for isolated prompt photons.  The thesis also describes a search for the Higgs boson in which the analysis techniques used in the measurement are exploited to reduce and estimate non-prompt backgrounds in diphoton events.