Lebanon () is a city in and the county seat of Lebanon County, Pennsylvania, United States. The population was 25,477 at the 2010 census, a 4.2% increase from the 2000 count of 24,461. Lebanon is located in the central part of the Lebanon Valley, 26 miles (42 km) east of Harrisburg and 29 miles (47 km) west of Reading.
Lebanon was founded by George Steitz in 1740 and was originally named Steitztown.
Native tribes in the area of what is now Lebanon included the Shawnee, Susquehannock, Gawanese, Lenape (or Delaware), and Nanticoke peoples.
Lebanon was settled by European colonists in 1720, many with the family names of "Steitz" and "Light", along a creek that was then named "Steitz Creek". The Light patriarchs built a fort to protect against Indians and named it "Light's Fort". The town was laid out in 1753, incorporated as a borough on February 20, 1821, and became a city on November 25, 1885. It adopted the commission form of government, consisting of four councilmen and a mayor.
Lebanon bologna was first made here. Lebanon was formerly home to a major steel mill operated by Bethlehem Steel.
According to the United States Census Bureau, the city has a total area of 4.2 square miles (11 km2), all of it land.