Mount Gretna is a borough in Lebanon County, Pennsylvania, United States. It is part of the Lebanon, PA, Metropolitan statistical area. The population was 188 at the 2020 census. The borough was founded by the Pennsylvania Chautauqua Society, which was attracted by the area's natural landscape and beauty, by the 1890s.

Lebanon County is a county in the Commonwealth of Pennsylvania, United States. As of the 2020 census, the population was 143,257. Its county seat is the city of Lebanon. It lies 72 miles northwest of Philadelphia, which is the nearest major city. The county is part of the South Central Pennsylvania region of the state.