Naugatuck (/ˈnɔːɡətʌk/; NAW-gə-tuhk) is a consolidated borough and town in New Haven County, Connecticut, United States. The town, part of the Naugatuck Valley Planning Region, had a population of 31,519 as of the 2020 census.

The town spans both sides of the Naugatuck River just south of Waterbury and includes the communities of Union City on the east side of the river, Straitsville on the southeast (along Route 63), and Millville on the west (along Rubber Avenue).

Settlement began as early as 1702. Samuel Hickox (1669–1713), credited as Naugatuck’s first settler, established a fulling mill on Fulling Mill Brook in 1709. The locality was known as Judds Meadow until 1752, when it was renamed Salem Bridge.

In 1844, parts of Waterbury, Bethany, and Oxford incorporated as the town of Naugatuck. The Borough of Naugatuck was established in 1893 and became coextensive with the town in 1895.

As the Industrial Revolution accelerated, Naugatuck developed a diverse manufacturing base and became a center of the rubber industry. In 1892, nine firms consolidated to form the United States Rubber Company (later Uniroyal Inc.), organized in Naugatuck, which for decades kept major operations in the borough. In 1936, U.S. Rubber introduced Naugahyde, a vinyl-coated fabric invented by company chemists in Naugatuck; the material was manufactured locally for many years.

The United States Rubber Company also created the Naugatuck Chemical Company in the early 20th century; the business later became Uniroyal Chemical and relocated major operations to Middlebury, Connecticut in the 1970s.

The Risdon Manufacturing Company, established in Naugatuck in the early 1900s, became a leading maker of metal closures and cosmetic packaging and later operated regionally under Crown Risdon.

In the 1960s, Harold Barber founded H. Barber and Sons, which designs and builds beach-cleaning equipment and has claimed to be the largest such business in the world.