The cost of energy as part of the total production costs in the cement industry is significant, typically at 20 to 40% of operational costs, warranting attention for energy efficiency to improve the bottom line. Historically, energy intensity has declined, although more recently energy intensity seems to have stabilized with the gains. Coal and coke are currently the primary fuels for the sector, supplanting the dominance of natural gas in the 1970s. A variety of waste fuels, including tires, steadily increase their share in fuel use. Between 1970 and 2010, primary physical energy intensity for cement production dropped 1.2% per year from 7.3 MBtu/short ton to 4.5 MBtu/short ton. Carbon dioxide intensity due to fuel consumption and raw material calcination dropped 24%, from 610 lb C/ton of cement (0.31 tC/tonne) to 469 lb C/ton cement (0.23 tC/tonne). Despite the historic progress, there is ample room for energy efficiency improvement. The share of wet-process plants decreased from 60% in 1970 to about 7% of clinker production in 2010 in the U.S. The remaining plants suggest the existence of a considerable potential, when compared to other industrialized countries. We examined over 50 energy-efficient technologies and measures and estimated energy savings, carbon dioxide emission savings, investment costs, and operation and maintenance costs for each of the measures. The report describes the measures and experiences of cement plants around the world with these practices and technologies. Substantial potential for energy efficiency improvement exists in the cement industry and in individual plants. A portion of this potential will be achieved as part of (natural) modernization and expansion of existing facilities, as well as construction of new plants in particular regions. Still, a relatively large potential for improved energy management practices exists.