OCM may refer to:

• Observe, copy, modify, also known as observe, imitate, modify.
• OCM (gene), also known as LOC4951, a human gene
• O'Callaghans Mills, a small village in Ireland (local folkloric slang)
• Occupy Central Movement
• Ocean Colour Monitor, an instrument launched on the IRS-P4 satellite on 1999-May-26
• Office for Coordination and Management, a component of the European Space Agency
• Ohio Community Media, a newspaper company in the United States
• Oil cleansing method, an alleged skin-cleansing method
• Oil content meter, a measuring device used on Marine Oily Water Separators
• Oil-Cut Mud, in oil drilling parlance
• Oka Chinna Maata,
• Olympic Council of Malaysia
• On-camera meteorologist
• One Caribbean Media
• Online Condition Monitoring, for maintenance
• Open Cloud Manifesto, also known as the Cloud Computing Manifesto
• Optical Channel Monitor, a device for optical performance monitoring in fiber-optic communications networks
• Oracle Certified Master, a designation in the Oracle Certification Program
• Oracle Configuration Manager, a service of Oracle Corporation
• Ordo Sancti Constantini Magni, Order of Saint Constantine the Great
• Organisation civile et militaire (English "Civilian and Military Organisation"), a group of the French Resistance
• Organizational Change Management
• Oriental Carpet Manufacturers, a London-based company involved in the production of, and trade with, Oriental carpets
• Oxidative coupling of methane
• Boolgeeda Airport, IATA airport code "OCM"