A suburb of Dayton, Washington Township is the largest of nine townships of Montgomery County, Ohio, United States.

[5] In 1833, Washington Township contained four gristmills, seven saw mills, and one cotton factory.

[6] The township is governed by a three-member board of trustees who are elected in November of odd-numbered years to a four-year term beginning on the following January 1.

Both the township's library system and the Centerville City School District (shared with residents of the city of Centerville) are ranked highly on state and national scales.

[8][9] Police services are provided in the township through a contract with the Montgomery County Sheriff’s Office.