Hartley is a census-designated place (CDP) in Solano County, California.

[2] The 2010 United States census reported Hartley's population was 2,510.

According to the United States Census Bureau, the CDP covers an area of 6.5 square miles (16.8 km2), 99.57% of it land and 0.43% of it water.

159 households (18.3%) were made up of individuals, and 54 (6.2%) had someone living alone who was 65 years of age or older.

There were 949 housing units at an average density of 145.9 per square mile (56.3/km2), of which 80.5% were owner-occupied and 19.5% were occupied by renters.