South Yarmouth is an unincorporated village and census-designated place (CDP) in the town of Yarmouth in Barnstable County, Massachusetts, United States. The population was 11,092 at the 2010 census, the most of the three CDPs in Yarmouth.
South Yarmouth is located in the southeast quarter of the town of Yarmouth at 41°40′4″N 70°11′59″W (41.667908, -70.199774). It is bordered by the CDP of West Yarmouth to the west and West Dennis to the east. U.S. Route 6, the Mid-Cape Highway, is to the north, beyond which is the CDP of Yarmouth Port.
According to the United States Census Bureau, the CDP has a total area of 7.8 square miles (20.2 km2). 6.9 square miles (18.0 km2) of it is land, and 0.85 square miles (2.2 km2) of it (10.94%) is water.
As of the census of 2000, there were 11,603 people, 5,485 households, and 3,181 families residing in the CDP. The population density was 640.0/km2 (1,656.9/mi2). There were 7,834 housing units at an average density of 432.1/km2 (1,118.7/mi2). The racial makeup of the CDP was 94.74% White, 1.53% African American, 0.34% Native American, 0.63% Asian, 0.06% Pacific Islander, 1.03% from other races, and 1.66% from two or more races. Hispanic or Latino of any race were 1.63% of the population.