CES may stand for:

• Closed ecological system, isolated from the outside
• Clean Energy Standards
• Constant elasticity of substitution, in economics, a feature of a particular class of production function
• The ISO 639 code for the Czech language
• CES, annual technology trade show in Las Vegas produced by the Consumer Technology Association

• Circuit Emulation Service, a telecommunication technology
• Cryogenic energy storage
• Character encoding scheme, a reversible transformation of sequences of code units to sequences of bytes
• Charge-exchange spectroscopy, a diagnostic used in plasma physics

• ICAO Code designator for China Eastern Airlines

• Cauda equina syndrome, a serious neurological condition
• Cranial electrotherapy stimulation, therapeutic brain stimulation
• Camurati-Engelmann disease, also called "Camurati Engelmann syndrome" (CES)
• Carboxylesterase, an enzyme that catalyzes the reaction between a carboxylic ester and water

• Caspian Engineers Society
• Center for Economic Studies, University of Munich
• Center for Ethical Solutions, bioethics think tank in the United States
• Centre for Environmental Studies, former UK research organization
• Church Educational System, of The Church of Jesus Christ of Latter-day Saints
• Coalition for Economic Survival, a Los Angeles–based community organization
• Coalition of Essential Schools, US educational reform
• Community Exchange System, international Internet trading network
• Commonwealth Employment Service, former Australian Government employment agency
• Confédération Européenne de Scoutisme or Confederation of European Scouts
• Centre for European Studies (disambiguation), the name of several educational institutions
• Center for Election Science, a US-based Approval voting advocacy organization

• Jean Ces, French boxer of the 1920s

• Central South station, a proposed MTR station in Hong Kong
• Cessnock Airport, IATA airport code "CES"
• Cressing railway station, British railway station with station code CES