The cosmic-ray energetics and mass (CREAM) investigation is designed to measure cosmic-ray composition to the supernova energy scale of 10 15 eV in a series of ultra long duration balloon (ULDB) flights. The first flight is planned to be launched from Antarctica in December 2004. The goal is to observe cosmic-ray spectral features and/or abundance changes that might signify a limit to supernova acceleration. The particle charge ( Z) measurements will be made with a timing-based charge detector and a pixelated silicon charge detector to minimize the effect of backscatter from the calorimeter. The particle energy measurements will be made with a transition radiation detector (TRD) for Z>3 and a sampling tungsten/scintillator calorimeter for Z⩾1 particles, allowing inflight cross calibration of the two detectors. The status of the payload construction and flight preparation are reported in this paper.