Shield
Or, six pallets couped Gules, a ship of Cabrillo's time Argent; on a canton Azure a fleur-de-lis encircled by a garland of laurel of the first.
Crest
That for the regiments and separate battalions of the California Army National Guard: On a wreath of the colors Or and Gules, the setting sun behind a grizzly bear passant on a grassy field, all Proper.
Motto
WE AIM TO HIT.
Shield
The shield is red for Artillery. The six pallets couped produce a diminished bordure effect on the shield and represent the six batteries comprising the Regiment at the time of its organization. The ship is a representation of the ship of Don Juan Rodrigues Cabrillo, a Portuguese, who discovered San Diego Harbor. The charges on the canton, the fleur-de-lis encircled by a garland of laurel, are taken from the coat of arms of the 250th Coast Artillery, as Batter B of the 251st Coast Artillery, California National Guard, is a descendant of Batter F of the 250th Coast Artillery, California National Guard which served during World War I as B Battery of the 65th Coast Artillery (US).
Crest
The crest is that of the California Army National Guard.
The coat of arms was originally approved for the 251st Coast Artillery (Harbor Defense) on 9 January 1928. It was redesignated for the 746th Antiaircraft Artillery Gun Battalion on 7 January 1952. The insignia was redesignated for the 251st Artillery Regiment on 16 February 1961. It was redesignated for the 251st Air Defense Artillery Regiment on 10 July 1972.