The Mu2e experiment will study charged lepton flavor violation by searching for a neutrinoless, coherent conversion of a mu- to an e-. Such a process will result in an electron of 105 MeV energy. A major background source comes from cosmic-ray muons which can produce electrons that mimic these conversion electrons at a rate of approximately one per day. An active veto detector surrounding the apparatus will be used to detect incoming cosmic-ray muons.