DCO may refer to: Diploma in Community Ophthalmology
Astronomy Dark compact object, a dark compact star
Technology Device configuration overlay, of a computer hard disk drive Digitally controlled oscillator, in electronics Siemens DCO, a telephone switch Drift City Online, a game Domain controller, on Microsoft Servers Developer Certificate of Origin, used in open source software projects to verify individual contributions
Other Deep Carbon Observatory Development Consent Order, the means of obtaining permission for nationally significant projects in England and Wales Digital Cooperation Organization, an international organization Dimension Century Orguss, anime series Direct commission officer, a military rank Disney Channel Original (disambiguation) District coordination officer, a civil service position in Pakistan Driver-controlled operation, a method of manually operating a train The British Columbia Regiment (Duke of Connaught's Own), a regiment of the Canadian Forces Duke of Cambridge's Own, a.k.a. Middlesex Regiment Dynamic Creative Optimization, a term used in programmatic marketing D.Co., an abbreviation used for the United States District Court for the District of Colorado Docket Control Order, a legal document used to confirm court deadlines. Document Control Officer controls access to documents that are restricted to certain people