  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 $\approx 10 fb^{-1}$.
