The 3rd Regiment California Volunteer Infantry was an infantry regiment in the Union Army during the American Civil War. This regiment was organized at Stockton and at Benicia Barracks, from October 31 to December 31, 1861, to serve three years. The regiment was first commanded by Colonel Patrick Edward Connor. After the formation of the regiment at Stockton, four companies were sent to Humboldt County during the month of November, 1861. During the month of July, 1862, Colonel Connor was sent, with his regiment, to the District of Utah, in which it was on duty for the balance of its term of service.