The authors feel very honored to have been chosen to review and update this chapter on Thermal Properties, originally written in 1965 by L. J. Mitchell, a supervisory engineer with the Bureau of Reclamation, Denver, Colorado, and later updated by J. A. Rhodes, who retired in 1980 as chief of the Concrete Branch, Office Chief of Engineers. At the time of authoring this chapter, their total experience dealing with thermal properties of mass concrete approached 60 years.