U.S. light and medium tank companies, whether assigned to tank battalions in armored divisions, separate tank battalions, or tank companies in cavalry reconnaissance squadrons, had either 17 or 18 tanks. The only major outward difference between the two is that the light tank company lacked an M4 assault gun. When the vehicle was authorized in the new table of organization and equipment but was not yet actually available, tank battalions in Europe immediately after D-Day often used a normal 75-mm armed Sherman in place of the assault gun in the medium tank companies, and those in Italy often used the M7 Priest 105 mm howitzer motor carriage (logically, somewhat more suitable) as a stopgap until the 105 mm-armed Sherman became available; it took far longer to arrive in the latter theater.

The structure of the light and medium tank company was very similar per respective T/O&Es 17-17 and 17-27, both issued on 11 November 1944. Each of the three platoons had five tanks, and there were two tanks in the company headquarters section, with the latter company having an M4 assault gun to go along. Space was provided in one of the regular tanks for the company commander, and the other tank was used as a spare. The medium tank company's headquarters section also had a 2 1/2-ton truck. The company headquarters of both companies also had a maintenance section with a tank recovery vehicle, halftrack with 1-ton trailer, and a jeep with a 1/4-ton trailer. The administrative, supply, and mess section had a 2 1/2 ton truck for the company kitchen. The strength of the light tank company was 5 officers and 94 enlisted men; the medium tank company 5 officers and 112 enlisted men.