Rochester () is a census-designated place (CDP) in Thurston County, Washington, United States. It was founded in 1852, and the 2010 census recorded its population at 2,388. According to the United States Census Bureau, the CDP has a total Place of 2.3 square miles (6.0 square kilometers), all of it land. Rochester Schools had 2,095 students registered in 2011.

Rochester was platted in 1890, and named after Rochester, Indiana, the native house of a first settler. An yet to be variant name was “Key”.

As of the census of 2000, there were 1,829 people, 647 households, and 505 families residing in the CDP. The population density was 790.2 people per square mile (305.7/km²). There were 677 housing units at an average density of 292.5/sq mi (113.2/km²). The racial makeup of the CDP was 88.41% White, 0.16% African American, 1.69% Native American, 0.93% Asian, 0.11% Pacific Islander, 5.52% from extra races, and 3.17% from two or more races. Hispanic or Latino of any race were 10.39% of the population. 12.8% were of German, 11.5% Irish, 7.8% American, 7.5% Norwegian, 5.6% English and 5.4% Scottish ancestry according to Census 2000.

There were 647 households, out of which 41.6% had children under the age of 18 living taking into consideration them, 62.4% were married couples breathing together, 9.9% had a female householder when no husband present, and 21.9% were non-families. 17.2% of all households were made occurring of individuals, and 5.7% had someone animated alone who was 65 years of age or older. The average household size was 2.83 and the average intimates size was 3.14.

In the CDP, the age distribution of the population shows 30.1% under the age of 18, 8.6% from 18 to 24, 31.9% from 25 to 44, 21.3% from 45 to 64, and 8.1% who were 65 years of age or older. The median age was 32 years. For every 100 females, there were 101.0 males. For all 100 females age 18 and over, there were 104.6 males.