borough (town), Butler county, western Pennsylvania, U.S., on Connoquenessing Creek, 25 miles (40 km) north of Pittsburgh. It is known as the first settlement in America of the Harmonist Society (Rappites) led by George Rapp (Rapp, George), an immigrant from Württemberg, Germany, who held religious-communistic views and espoused celibacy. The town was laid out in 1805 as a “Community of Equality” and named Harmony for one of the society's principles. The graveyard (just southeast of the borough where more than 100 Harmonists lie buried), a few brick houses, the Harmony Museum, and the Tower Clock (1810–11; now housed in the museum) are reminders of the original settlers who in 1815 migrated to Indiana and founded New Harmony. Rapp's followers returned to Pennsylvania in 1825 and established the village of Economy (now Ambridge).

Oil, natural gas, coal, and iron deposits are characteristic of the vicinity. Harmony has acquired some light industry, and tourism is important. Pop. (1990) 1,054; (2000) 937.