Performance of the Transition Radiation Tracker in ATLAS using cosmic ray runs

The experimental physics program at the LHC is expected to begin this year at CERN. In preparation for this research, the detectors are being commissioned in a series of cosmic ray data runs. An overview of the ATLAS detector, the data collection and analysis, and studies in preparation for first physics will be given. In this talk, emphasis will be given to the performance of the Transition Radiation Tracker in the Inner Detector.