Alignment of the ATLAS Inner Detector tracking system

To reconstruct trajectories of charged particles produced in the LHC collisions, the ATLAS detector is equipped with an inner tracking system built using two different technologies, silicon planar sensors (pixels and microstrips) and drift-tube based detectors. Together they constitute the ATLAS Inner Detector, which is embedded in a 2 T solenoid field. An alignment of the inner tracking system, accurately determining the position and orientations of individual detector modules, is necessary for achieving required performance. The ATLAS Inner Detector has been aligned using isolated, high-pT collision tracks, and using cosmic-ray tracks collected between LHC proton-proton collisions. These proceedings present the alignment procedure, its results, and performance with LHC collision data during 2011. Results from real data are compared with Monte Carlo simulation of a perfectly aligned detector.