Thompsonville is a census-designated place (CDP) in Washington County, Pennsylvania, United States.

At the 2000 census there were 3,592 people, 1,228 households, and 1,024 families living in the CDP.

The population density was 1,753.8 people per square mile (677.1 people/km2).

There were 1,254 housing units at an average density of 612.3 per square mile (236.4/km2).

[3] Of the 1,228 households 34.7% had children under the age of 18 living with them, 76.8% were married couples living together, 4.3% had a female householder with no husband present, and 16.6% were non-families.