Charlestown Township is one of twelve townships in Clark County, Indiana. As of the 2010 census, its population was 13,450 and it contained 5,382 housing units.
Charlestown Township was organized in 1817.
According to the 2010 census, the township has a total area of , of which (or 99.08%) is land and (or 0.92%) is water.
The township contains several cemeteries: Armstrong Cemetery, Baird Cemetery (a.k.a. King), Bottorff, Caldwell (a.k.a. Lutz/Prather), Carter, Charlestown, Coble, County Poor Farm, Crace, Douglas, Faris, Fifty-four, Goodwin, Goodwin/Nicholson, Hammond, Hester-Rowland, Kessler (a.k.a. Faris II), Long, Mathes, McCormick (a.k.a. McCullough), McDonald, Meloy, Montgomery, Otisco Cemetery (a.k.a. Seedtick), Pleasant Grove, Robertson, Robinson, Salem Methodist Church, Shelby Cemetery, Silver Creek Cemetery, St. Michael's, James Stuart Plantation, Weimer, and Worrell/Worrall.