Darien is a coastal town in Fairfield County, Connecticut, United States. With a population of 21,499 and a land area of just under 13 square miles (34 km2), it is the smallest town on Connecticut's Gold Coast. The town is part of the Western Connecticut Planning Region. It has a high rate of marriage, and high average number of children per household.

Fairfield County is a county in the southwestern corner of the U.S. state of Connecticut. It is the most populous county in the state and was also its fastest-growing from 2010 to 2020. As of the 2020 census, the county's population was 957,419, representing 26.6% of Connecticut's overall population. The closest to the center of the New York metropolitan area, the county contains four of the state's top 7 largest cities—Bridgeport (1st), Stamford (2nd), Norwalk (6th), and Danbury (7th)—whose combined population of 433,368 is nearly half the county's total population.