Pleasanton is a city in Alameda County, California, United States. Located in the Amador Valley, it is a suburb in the East Bay region of the San Francisco Bay Area. The population was 79,871 at the 2020 census. In 2005 and 2007, Pleasanton was ranked the wealthiest middle-sized city in the United States by the Census Bureau. Pleasanton is home to the headquarters of Safeway, Workday, Ellie Mae, Roche Molecular Diagnostics, Blackhawk Network Holdings, Veeva Systems, and Simpson Manufacturing Company. Other major employers include Kaiser Permanente, Oracle and Macy's. Although Oakland is the Alameda County seat, a few county offices are located in Pleasanton. The Alameda County Fairgrounds are located in Pleasanton, where the county fair is held during the last week of June and the first week of July. Pleasanton Ridge Regional Park is located on the west side of town.

Alameda County is a county located in the U.S. state of California. As of the 2020 census, the population was 1,682,353, making it the 7th-most populous county in the state and 21st most populous nationally. The county seat is Oakland. Alameda County is in the San Francisco Bay Area, occupying much of the East Bay region.