We calculated the formation energies of all simple point defects in cubic fluorite structured using density functional theory within the GGA+ approximation. All possible defect charge states were considered, and also polarons and associates of polarons with oxygen vacancies: and . From the individual defect energies, we extracted Schottky, Frenkel, and anti-Frenkel energies: we find that anti-Frenkel disorder has the lowest energy in ceria. Energies for the reduction and the hydration of ceria are also computed, and the results are in good agreement with experiment. Finally, point-defect concentrations and conductivities are predicted for undoped and donor-doped systems as a function of oxygen partial pressure and temperature. The characteristic slopes found in experiment are reproduced.