Lacey is a city in Thurston County, Washington, United States. It is a suburb of Olympia with a population of 53,526 at the 2020 census, making it the 24th most populous city in Washington. Lacey is located along Interstate 5 between Olympia and the Nisqually River, which marks the border with Pierce County and Joint Base Lewis–McChord.

Thurston County is a county located in the U.S. state of Washington. As of the 2020 census, its population was 294,793. The county seat and largest city is Olympia, the state capital.