The board noted that the athletes sometimes work 50 to 60 hours a week, are subject to special rules that do not apply to the rest of the student population, are already compensated through scholarships and generate millions in revenue for universities.
The ruling can be read here.
CNN reported that the NCAA released a statement that it was disappointed with the ruling.
"We frequently hear from student-athletes, across all sports, that they participate to enhance their overall college experience and for the love of their sport, not to be paid," CNN quoted the statement from NCAA chief legal officer Donald Remy. "While improvements need to be made, we do not need to completely throw away a system that has helped literally millions of students over the past decade alone attend college."
Northwestern plans to challenge the ruling by the National Labor Relations Board and it could take years to resolve, CNN noted.
How would you feel if your favorite college team unionized?