  This contribution summarizes the discovery potential of the Standard Model Higgs boson using the $H \gamma \gamma$ decay with the ATLAS detector. The relevant detector performance aspects of photon reconstruction, photon identification and trigger issues are discussed. The potential of inclusive $H \gamma \gamma$ as well as Higgs boson searches in association with one or two hard jets are studied. The discovery potential is finally assessed using an unbinned multivariate maximum-likelihood fit with an expected integrated luminosity of $\approx 10 fb^{-1}$. 
Standard Model $H \gamma \gamma$ discovery potential with ATLAS