In 1918 the 33rd Division was organized as follows:

65th Infantry Brigade
129th Infantry Regiment
130th Infantry Regiment
123rd Machine Gun Battalion

66th Infantry Brigade
131st Infantry Regiment
132nd Infantry Regiment
124th Machine Gun Battalion

58th Field Artillery Brigade
122nd Field Artillery (75mm)
123rd Field Artillery (155mm)
124th Field Artillery (75mm)
108th Trench Mortar Battery

Divisional Troops:
122nd Machine Gun Battalion
108th Engineers
108th Field Signal Battalion
Headquarters Troop

Train
108th Train Headquarters & Military Police
108th Ammunition Train
108th Supply Train
108th Engineer Train
108th Sanitary Train, consisting of:

Inter-war Years
The 33rd Infantry Division was a National Guard division for the State of Illinois. It was federalized on 5 March 1941 at Chicago, Illinois. The 130th Infantry Regiment was formed that same day. The division participated in the 1941 Arkansas and Louisiana Maneuvers. It contained:

65th Infantry Brigade HHC
129th Infantry Regiment
130th Infantry Regiment

66th Infantry Brigade HHC
131st Infantry Regiment
132nd Infantry Regiment

58th HHB Division Artillery
122nd Field Artillery Regiment (75mm)
124th Field Artillery Regiment (75mm)
123rd Field Artillery Regiment (155mm)

Headquarters 33rd Division
HQs & HQs Detachment
Medical Detachment
Headquarters Company
33rd Military Police Company
33rd Signal Company
108th Ordnance Company
108th Engineers (Combat) Regiment
108th Medical Regiment
108th Quartermaster Regiment

Special Troops
33rd Tank Company (later re-designated Company B/192nd Tank Battalion)

World War II
The division, along with the other National Guard divisions, was ordered to convert from the square to the triangular formation between January and February 1942. The 108th Engineers (Combat) Regiment was broken up on 12 February 1942 and the HQ, HQ and Service Company, and Companies A, B, and C became the 108th Engineer Combat Battalion, which remained with the division. The HQ, 1st Battalion was inactivated on 21 February 1942 and the 2nd Battalion became the 181st Battalion (Heavy Pontoon), an engineering unit.

The 132nd Infantry Regiment was detached on 14 January 1942. On 21 February 1942 the division was re-designated the 33rd Infantry Division. That same day the 131st Infantry Regiment was detached. The 129th Infantry Regiment was detached on 31 July 1943. The 136th Infantry Regiment was formed and assigned to the division on 1 April 1942 and the 123rd Infantry Regiment was formed and assigned to the division on 28 September 1942. The division served in the south Pacific, fighting in New Guinea and in the Philippines. In 1944/1945 the division contained:

123rd Infantry Regiment
130th Infantry Regiment
136th Infantry Regiment

HHB Division Artillery
123rd Field Artillery Battalion (155mm)
122nd Field Artillery Battalion (105mm)
124th Field Artillery Battalion (105mm)
210th Field Artillery Battalion (105mm)

33rd Reconnaissance Troop, Mechanized
108th Engineer Combat Battalion
108th Medical Battalion
33rd Counter-Intelligence Corps Detachment
Headquarters Special Troops
Headquarters Company, 33rd Division
33rd Military Police Platoon
733rd Ordnance Light Maintenance Company
33rd Quartermaster Company
33rd Signal Company
33rd Band

During its combat operations, divisions usually had various units attached in support of it and other organic units detached. Where those attachments and detachments are well-documented for the divisions that fought in the European Theater of Operations, no such documentation was found for this division, which fought in the Pacific.

The division formed part of the occupation forces of the Japanese home islands and was inactivated there on 28 February 1946.

Order of Battle from Nafziger, US Army in World War Two, Volume 1.