ATLAS Trigger Performance and Initial Running

An efficient trigger will be crucial to charged Higgs boson searches at the LHC. The ATLAS trigger will need to achieve a rejection factor of about 10^7 against random proton-proton collisions, and still be able to efficiently select signal events. Commissioning of the ATLAS trigger is progressing well, and much has already been done using cosmic rays and by replaying simulated physics events through the system. Detailed plans have been developed for commissioning with single LHC beams and the first collisions. The evolution of the ATLAS trigger towards stable running will be discussed in view of the searches for the charged Higgs boson. In particular, the determination of the trigger efficiency will be discussed, both in the case of the inclusive lepton triggers and the combined triggers needed for charged Higgs boson searches.