Adin is a census-designated place in Modoc County, California. It is located 29 miles southwest of Alturas, at an elevation of 4,203 feet. Its population is 205 as of the 2020 census, down from 272 from the 2010 census. Each summer, the town hosts the annual Golden State Star Party, a gathering of amateur and professional astronomers from California and parts of the United States.