The Cosmic Origins Spectrograph (COS) is a new instrument for the Hubble Space Telescope that will be installed during servicing mission 4, currently scheduled for May, 2005. The primary science objectives of the mission are the study of the origins of large scale structure in the universe, the formation, and evolution of galaxies, the origin of stellar and planetary systems and the cold interstellar medium. As such, COS has been designed for the highest possible sensitivity on point sources, while maintaining moderate (λ/Δλ = 20,000) spectral resolution. COS has recently (summer 2003) completed an initial calibration. Performance is essentially as predicted. Detailed results from that calibration are presented in Wilkinson, et al, this volume.