|Harmony Township,</br>Susquehanna County,</br> Pennsylvania|
|— Township —|
|- Type||Board of Supervisors|
|- Supervisor||Fred Jackson|
|- Supervisor||Darvin Green|
|- Supervisor||Oscar Miller|
|- Total||31.6 sq mi (82.0 km2)|
|- Land||31.4 sq mi (81.2 km2)|
|- Water||0.2 sq mi (0.8 km2)|
|- Density||17.8/sq mi (6.9/km2)|
|Time zone||Eastern (EST) (UTC-5)|
|- Summer (DST)||EDT (UTC-4)|
According to the United States Census Bureau, the township has a total area of 31.6 square miles (82.0 km²), of which, 31.4 square miles (81.2 km²) of it is land and 0.3 square miles (0.8 km²) of it (0.98%) is water.
Latter-day Saints believe that Joseph Smith, Jr. and Oliver Cowdery were visited by the angel of John the Baptist near Harmony in 1829, where he restored the keys to the Aaronic Priesthood. Joseph and Oliver subsequently baptized one another in the Susquehanna River.
As of the census of 2000, there were 558 people, 206 households, and 152 families residing in the township. The population density was 17.8 people per square mile (6.9/km²). There were 341 housing units at an average density of 10.9/sq mi (4.2/km²). The racial makeup of the township was 98.92% White, 0.90% Asian and 0.18% Pacific Islander. Hispanic or Latino of any race were 1.97% of the population.
There were 206 households out of which 34.5% had children under the age of 18 living with them, 63.6% were married couples living together, 5.3% had a female householder with no husband present, and 26.2% were non-families. 18.9% of all households were made up of individuals and 9.2% had someone living alone who was 65 years of age or older. The average household size was 2.71 and the average family size was 3.16.
In the township the population was spread out with 26.9% under the age of 18, 5.4% from 18 to 24, 27.6% from 25 to 44, 26.0% from 45 to 64, and 14.2% who were 65 years of age or older. The median age was 40 years. For every 100 females there were 98.6 males. For every 100 females age 18 and over, there were 94.3 males.
The median income for a household in the township was $31,579, and the median income for a family was $33,250. Males had a median income of $31,023 versus $16,667 for females. The per capita income for the township was $15,351. About 11.0% of families and 15.9% of the population were below the poverty line, including 22.5% of those under age 18 and 9.0% of those age 65 or over.