The National Letter of Intent signing is part of the NCAA experience, but not the NAIA experience. The NAIA student guide has this to say about National Letters of Intent, "Currently the NAIA does not recognize letters of intent however, some NAIA conferences do." Check with your NAIA schools of interest first for details about your their policies, but this article will concern itself with NCAA Letters of Intent only.
Further, the National Letter of Intent process does not apply to service academies or Ivy League schools. Only institutions that offer athletic scholarships are part of the NLI program. It is true, however, that service academies, Ivy League schools, and many NAIA schools routinely provide "signing papers" for prospective athletes coming to their schools to allow those athletes to have something to sign at signing parties back at their own high school. Such signing papers, however, do not have the legal standing of National Letters of Intent.
At bottom, the National Letter of Intent is a binding agreement that requires the school to provide the specified amount athletic-based financial aid for academic year (either two semesters or three quarters) and requires the student to attend the same institution for that same full academic year. Failure to complete the requirements of the agreement on the part of the student carries a penalty of a minimum of one full year of attendance at the next NLI institution attended and a loss of one full year of eligibility in all sports, not just the sport for which the NLI was signed.
Probably the question most frequently encountered question with respect to National Letters of Intent is, "What if the coach I sign under moves on to another institution?" The answer to that is that the NLI binds the student-athlete to the institution. The terms of the National Letter of Intent are unaltered by coaching changes. Countless student-athletes deal with this situation every year, but the institution is not bound to release the student-athlete from the terms of the letter. The student-athlete, however, may file a request for release from the terms of the NLI with the institution.
The request-for-release process involves going to the National Letter of Intent website (linked below) and filling out a Release Request Form. This form must be submitted to both the signing institution and the National Letter of Intent office. The signing institution has up to 30 days to grant or deny the request for release and return the form to all parties. If the signing institution denies the request, the student-athlete is bound by the terms of the agreement. In this case, the signing institution may or may not allow other coaches to recruit the athlete in question.
If the institution approves the request, the student-athlete is given a Complete Release and is free to be recruited by other institutions but may not sign another National Letter of Intent that year. No other coaches may recruit the student-athlete, however, until a release has been granted.
Any of several circumstances can render a National Letter of Intent null and void. Like a Complete Release, each of these conditions do preclude the student-athlete from signing another National Letter of Intent that same year. Conditions which can render the National Letter of Intent null and void include, but are not limited to: not gaining admission to the institution in question (as a rule of thumb, it's not a good idea to be signing a National Letter of Intent at a school for which you have not already been granted admission), not meeting NCAA, institutional, or conference eligibility requirements, service in the armed forces and on a church mission, and the signing institution discontinuing the sport for which you signed.
There are specific periods of time when National Letters of Intent may be signed. For track and field/cross country, this period spans from February 6 to August 1 for the 2013-14 academic year. Signing periods for future academic years have not been determined at the time of this writing.
Verbal commitments from the coach and the student-athlete, no matter when they are given, are not binding until the National Letter of Intent is signed. Other coaches may or may not abandon their recruiting efforts for the athlete in question when a verbal commitment is given, but the coaches are not required to do so. No binding commitment may be made, either by the coach or by the athlete, until the signing period begins. No verbal commitment becomes binding, even if issued between February 6 and August 1, until a National Letter of Intent has been signed. Once a National Letter of Intent has been signed, all other NCAA coaches must terminate any recruiting efforts for that athlete.
Some fairly specific rules govern the delivery of and signing of the Natiional Letter of Intent. No coach or other institutional representative may hand deliver the National Letter of Intent to the prospective student-athlete's home or school or be on hand for the signing. This rule is intended to prevent there being any undue pressure on the prospective student-athlete to sign the document. Permissible delivery methods include mail, e-mail, fax, express mail, and courier service.
Experience tells me that a National Letter of Intent might occasionally be delivered to a school "out of the blue," without any expectation on the part of the prospective student-athlete that he/she would receive a National Letter of Intent from that school or coach. A prospective student-athlete is not under obligation to sign a National Letter of Intent simply because it has been delivered for signing. Presumably, the athlete and coach in question have agreed in advance and in principle that the coach will send, and the athlete will sign, a National Letter of Intent, but it doesn't always happen exactly that cleanly.
When delivered, there are two copies of the National Letter of Intent, one to be returned to the institution and one to be retained by the student-athlete. The NLI must be accompanied by a financial aid agreement. No release agreements from the institution may accompany the signing documents. The student-athlete has up to 14 days from the date of issue to sign the National Letter of Intent. The NLI must include a parent or legal guardian signature unless the student-athlete has reached age 21, regardless of the marital status of the student athlete.
Once signed, the student-athlete returns the National Letter of Intent to the institution and the document must be filed with the institution's conference for validation within 21 days of the date signed.