Lake Louise Winter Institute 2010: ATLAS Commissioning with Data

After an extensive period of commissioning with cosmic rays, the ATLAS detector received a brief period of single-proton beam, followed by nearly a month of proton-proton collisions from the LHC. Most of the collisions were at a center-of-mass energy of 0.9 TeV, with a short period at 2.36 TeV. The focus of this running period was to commission ATLAS for the 2010 collision run during which physics results are expected. In this talk, we will show how early collision data has been used to commission the triggering system, the tracking system, and the calorimeters of ATLAS.