Although most people under the age of 18 are legally considered to be minors, the United States Marine Corps does allow applicants who are 17 years old to join its ranks. To do this, however, applicants must undertake certain steps to ensure that their enlistment is legal under federal law. In almost all cases, a Marine Corps recruiter will guide applicants through the process.

Speak to a Marine Corps recruiter. Recruiters process new enlistees and help them navigate the paperwork required to enlist in the military. A recruiter will walk applicants through the process for joining as well as keep them up to date on the various eligibility criteria.

Graduate from high school or earn a GED. In all cases, the Marine Corps requires a high school diploma or its equivalent to enter training. While recruits can begin the enlistment process without a degree, they must have graduated prior to shipping out for training. In rare cases, an applicant without a high school diploma that attended school until the completion of the 10th grade can enlist in the Marine Corps. They are subject to stricter requirements.

Obtain consent from both parents. This step is mandated by federal law for 17-year-old applicants and, in all but the rarest circumstances, must be completed prior to enlistment. Both parents will be required to sign under Section VI of the DD Form 1966. This form is a record of an applicant's military processing.

Take the Armed Services Vocational Aptitude Battery (ASVAB). This test is required for all incoming recruits and is an aptitude exam that will help place them into a job within the Marine Corps.

Undergo a physical at a Military Entrance Processing Station (MEPS). This entrance physical is required for all new recruits and screens them for a variety of diseases and conditions in addition to drug use.