Lafayette is a city in Contra Costa County, California, United States. As of 2011, the city's population was estimated to be 24,285. It was named after the Marquis de La Fayette, a French military hero of the American Revolutionary War. Today Lafayette is known for its pastoral rolling hills, good schools, and wealthy inhabitants. In 2016, the median household income in Lafayette was over $140,000, more than twice the statewide average and about two and half times the national median.