Mount Pleasant Township is a township in Washington County, Pennsylvania, in the United States. As of the 2000 census, the township population was 3,422.
According to the United States Census Bureau, the township has a total area of 35.7 square miles (92.5 km²), of which, 35.6 square miles (92.3 km²) of it is land and 0.1 square miles (0.2 km²) of it (0.22%) is water.
As of the census of 2000, there were 3,422 people, 1,279 households, and 1,006 families residing in the township. The population density was 96.0 people per square mile (37.1/km²). There were 1,348 housing units at an average density of 37.8/sq mi (14.6/km²). The racial makeup of the township was 96.49% White, 2.98% African American, 0.09% Asian, and 0.44% from two or more races. Hispanic or Latino of any race were 0.09% of the population.