Every year, over 2,000 new Marine officers are commissioned, and 38,000 recruits accepted and trained. All new Marines, enlisted or officer, are recruited by the Marine Corps Recruiting Command.

Commissioned officers are commissioned mainly through one of three sources: Naval Reserve Officer Training Corps (NROTC), Officer Candidates School (OCS), or the United States Naval Academy (USNA). Following commissioning, all Marine commissioned officers, regardless of accession route or further training requirements, attend The Basic School (TBS) at Marine Corps Base Quantico, Virginia. At TBS, second lieutenants, warrant officers, and selected foreign officers learn the art of infantry and combined arms warfare. Along with the concept that "Every Marine is a rifleman", every officer, regardless of his MOS/billet, is qualified to be an infantry platoon commander.

Enlisted Marines attend recruit training, known as boot camp, at either Marine Corps Recruit Depot San Diego or Marine Corps Recruit Depot Parris Island. Historically, the Mississippi River served as the dividing line which delineated who would be trained where, while more recently, a district system has ensured a more even distribution of male recruits between the two MCRD facilities. Females attend only the Parris Island depot as part of the segregated Fourth Recruit Training Battalion. All recruits must pass a fitness test to start training; those who fail receive individualized attention and training until the minimum standards are reached. Marine recruit training is the longest among the American military services; it is 13 weeks long, compared to the Army's 10 weeks or the Navy's 9 weeks.

Following recruit training, enlisted Marines then attend School of Infantry training at Camp Geiger or Camp Pendleton. Infantry Marines begin their combat training, which varies in length, immediately with the Infantry Training Battalion (ITB). Marines in all other MOSs other than infantry train for 29 days in Marine Combat Training (MCT), learning common infantry skills, before continuing on to their MOS schools which vary in length.

United States Marine Corps Recruit Training, commonly known as "boot camp", is a program of initial training that each recruit must successfully complete in order to join the United States Marine Corps. All enlisted individuals entering the Marine Corps, regardless of eventual active or reserve duty status, will undergo recruit training at one of the two Marine Corps Recruit Depots (MCRD): Parris Island, South Carolina, or San Diego, California. Male recruits from the 8th, 9th and 12th recruiting districts (predominantly areas west of the Mississippi River) are sent to MCRD San Diego. Male recruits from 1st, 4th and 6th recruiting districts, as well as all female recruits, are sent to Parris Island.

Those desiring to become officers attend training at Officer Candidates School, United States Naval Academy, or Reserve Officer Training Corps.

Marines generally hold that their recruit training is the most physically and mentally difficult amongst the Uniformed Services, often by citing that it is longer, a more demanding Physical Fitness Test (PFT), and the strictest height and weight standards.