| 3rd Battalion, 23rd Marine Regiment | |
|---|---|
 3rd Battalion, 23rd Marine insignia | |
| Active | 22 July 1942 – 10 November 1945 1 July 1962 – present |
| Country | United States of America |
| Branch | United States Marine Corps |
| Type | Infantry regiment |
| Role | Locate, close with and destroy the enemy with fire and maneuver |
| Size | 1,000 |
| Part of | 23rd Marine Regiment 4th Marine Division |
| Garrison/HQ | Saint Louis, Missouri |
| Motto(s) | "Non Sibi, Sed Patria" |
| Engagements | World War II
|
| Commanders | |
| Current commander | Lieutenant Colonel Cameron D. McCoy |
| Notable commanders | John R. Lanigan |
3rd Battalion, 23rd Marine Regiment (3/23) is a reserve infantry battalion in the United States Marine Corps located throughout the Southern United States consisting of approximately 800 Marines and Sailors. The battalion was first formed in 1943 for service in the Central Pacific Area during World War II, taking part in a number of significant battles including those at Saipan and Iwo Jima before being deactivated at the end of the war. In the early 1960s, the unit was reactivated as a reserve battalion. The battalion is headquartered in Saint Louis, Missouri, with outlying units throughout the Southern United States. 3/23 falls under the command of the 23rd Marine Regiment and the 4th Marine Division. Recent operations have included tours in Iraq and Afghanistan.