Fredericksburg is an unincorporated community in Posey Township, Washington County, in the U.S. state of Indiana.

[5] It was named for Frederick Royse, the original owner of the town site.

[10] It is located on the Blue River, just downriver from the confluence of its North and South Forks.

There were 41 housing units at an average density of 41.4 per square mile (16.0/km2).

The racial makeup of the town was 92.9% White, 2.4% Native American, and 4.7% from two or more races.

37.1% of all households were made up of individuals, and 20% had someone living alone who was 65 years of age or older.

31.7% of all households were made up of individuals, and 9.8% had someone living alone who was 65 years of age or older.

There were 21.4% of families and 23.5% of the population living below the poverty line, including 19.0% of under eighteens and 23.1% of those over 64.