Jefferson Township is one of twelve townships in Adams County, Indiana. As of the 2020 census, its population was 1,363, up from 1,089 at the previous census.
According to the "2020 American Community Survey 5-Year Estimates", 33.9% of the township's population spoke only English, while 63.9 spoke an "other [than Spanish] Indo-European language" (basically Pennsylvania German/German).
According to the 2010 census, the township has a total area of , of which (or 99.88%) is land and (or 0.12%) is water.
The township contains the following cemeteries: Loofborrow, Rumple (also known as Cook- no longer exists), and St. Mary Catholic.