A headquarters and service company is a company-sized military unit, found at the battalion and regimental level in the U.S. Marine Corps.
In identifying a specific headquarters unit, it is usually referred to by its abbreviation as H&S company or HSC.
At the regimental level, the headquarters company is significantly smaller, having an authorized strength of only 182 members.
Also, there is no scout sniper platoon in the regimental H&S Company, making the S-2 section smaller, further reducing manpower totals.
While the company commander of a regimental H&S company remains as a captain, the ranks of many of the staff and support personnel are typically higher than those found at the battalion level to reflect the greater degree of responsibility and authority resident in a higher echelon of command.
The S-3 and S-4 sections are slightly larger (perhaps reflecting the greater responsibility for planning and supervising current and future operations inherent in these staff sections) and there is a somewhat larger communications platoon (largely due to significantly greater allocation of manpower in the regimental communications center as compared to the battalion's message center).