Cos Cob is a neighborhood and census-designated place in the town of Greenwich, Connecticut. It is located on the Connecticut shoreline in southern Fairfield County. It had a population of 6,770 at the 2010 census.
Cos Cob is located on the western side of the mouth of the Mianus River. The American Impressionist Cos Cob Art Colony flourished in the late 19th and early 20th centuries. An offshoot of the group, the Greenwich Art Society, continues to support local artists in town.
The town of Greenwich is one political and taxing body, but consists of several distinct sections or neighborhoods, such as Banksville, Byram, Cos Cob, Glenville, Mianus, Old Greenwich, Riverside and Greenwich (sometimes referred to as central, or downtown, Greenwich). Of these neighborhoods, three (Cos Cob, Old Greenwich, and Riverside) have separate postal names and ZIP codes. From 1883 to 1885, the official post office name of Cos Cob was Bayport.
In 2015, Forbes ranked Cos Cob the 287th wealthiest place in the US with a median house sale price of $1,329,107.