Being a non professional athlete (an amateur) is one of the most important athletic requirements to compete for a college or university in the USA.
Each league has rules and general definitions of what it means being a professional player; moreover there are particular regulations for certain sports. There are differences for team and individual sports and specific rules for those sports for which it exists a professional league in the USA (such as american football, basketball, ice hockey, baseball, soccer, etc.) or for those sports for which it exists a professional circuit such as tennis, track and field and golf.
Independently of these rules, there's one general rule which is the core of why an athlete may be considered a professional and that is if he or she has received money in any form that will exceed the amount needed for that athlete to practice and compete in the sport.
The NJCAA is also a bit more restrictive, and an athlete maybe considered professional just for playing in a team in which a professional (or former professional) player plays. This rule applies only after the 19th birthday of the PSA or whenever he or she starts university; the rule specifically states: "An individual loses amateur status and thus shall not be eligible for intercollegiate competition in a NJCAA certified sport if they have participated with professional teams or professional players after full time enrollment at a college or have reached their 19th birthday, whichever comes first."
Other related information (registration needed)
- How can I know if I am considered an amateur athlete?
- Am I considered amateur if I've been with my national team or in the military corps?