The ATLAS detector at CERN has been collecting millions of cosmic rays (mostly muons) while waiting for collision data due to arrive next year. The cosmic data is very useful for studying the performance of the detector, contains interesting physics (spectrum, muon multiplicity, upward-going neutrino-induced muons, etc.), and is the main background to several signature of new physics such as Stopping Gluinos. This project will entail studying the cosmic ray data from ATLAS and exploring these topics.