Lamar County is a county located in the U.S. state of Mississippi. As of the 2020 census, the population was 64,222. Its county seat is Purvis. Named for Confederate Lucius Quintus Cincinnatus Lamar, the county was carved out of Marion County to the west in 1904.

Purvis is a U.S. city in and the county seat of Lamar County, Mississippi. It is part of the Hattiesburg, Mississippi Metropolitan Statistical Area. The population was 2,175 at the 2010 census. The Town of Purvis was incorporated on February 25, 1888 and was founded by and named after Thomas Melville Purves, originally of Marion County, Alabama. Purves, born March 8, 1820, was a second generation Scottish-American; his grandfather emigrated to Charleston, South Carolina in 1765.