The 154th Regiment (Regional Training Institute) ("Third Arkansas") is a training regiment/institute of the Army National Guard. Most of its history before the 1990s can be traced to the 154th Infantry Regiment which was created from the 1st and 2nd Battalions of the 3rd Arkansas Infantry Regiment, Arkansas National Guard, in 1917. The Regiment was activated as for World War I, re-designated as the 154th Infantry and shipped to France as a part of the 39th Infantry Division, but became a replacement regiment and its personnel were reassigned to other American Expeditionary Force (AEF) units.

The 39th Infantry Division was an infantry formation of the Army National Guard, originally formed as the 18th Division in 1917. The division consisted of troops from Arkansas, Louisiana, and Mississippi. After training at Camp Beauregard, Louisiana, the division was deployed to France but did not see combat before the end of World War I. In July 1923 the division was re-designated as the 31st Infantry Division. The 39th Infantry Division was reactivated after World War II with troops from Louisiana and Arkansas and its headquarters in Louisiana. In 1967, the 39th Infantry Division was reorganized to become the 39th Infantry Brigade (Separate). Its headquarters was in Little Rock and the unit consisted entirely of troops from Arkansas.