Neffsville is an unincorporated community in Manheim Township, Lancaster County, Pennsylvania, United States. As an unincorporated area, Neffsville has no formalized boundaries. The U.S. Geological Survey locates Neffsville at 40°6'0"N 76°18'20"W.

Manheim Township is a township in Lancaster County, Pennsylvania, United States. It was established in 1729. The township's southernmost border meets the city limits of Lancaster and includes the communities of Neffsville, Dillerville, and Landis Valley. Its population, as of the 2020 census, was 43,977 making it the second largest municipality in the county after Lancaster City.