The improved cosmetic quality, charge-transfer efficiency, and low noise of present-generation CCDs means that modern two-axis star trackers can measure star positions to accuracies of 1/50 of a pixel over the whole chip area. However, CCD selection, testing, screening for enhanced reliability, and careful attention to operating conditions are still necessary. This paper is concerned primarily with the performance, testing, and qualification of English Electric Valve Co. P8604 CCDs for use in star trackers for the German Roentgen-Satellit (ROSAT) x-ray astronomy satellite, although the tests developed should be widely applicable. It was found that the best-quality devices are essentially free of all image blemishes and have a white noise of 15 nV/Hz deferred charge of less than 1 %, response uniformity of 1.5% rms, and dark signal nonuniform ity at 40°C of 30 electrons rms. All of the candidate devices from flight batches passed a burn-in under voltage and temperature stress that are predicted to be equivalent to more than seven years' continuous mission operation.