Thomaston is a census-designated place (CDP) in Litchfield County, Connecticut, United States.

It extends to the south as far as Watertown Road, to the west beyond Hillside Cemetery and to Northfield Brook, to the north to a power line south of D. Welton Way, and to the east to Williams Street, Electric Avenue, and the Naugatuck River.

[2] U.S. Route 6 follows Main Street through Thomaston; it leads east to Bristol and southwest to Watertown.

The Connecticut Route 8 freeway passes east of the CDP, leading south 9 miles (14 km) to Waterbury.

Male full-time workers had a median income of $48,167 versus $52,788 for females.