Who Owns NPR?

National Public Radio (NPR) delivers breaking national and world news in addition to top stories in business, politics, health, science, technology, music and culture.

NPR is a private, not-for-profit corporation chartered by the District of Columbia and qualified by the Internal Revenue Service as a "501(c)(3)" organization exempt from taxation.

NPR is funded primarily by a single source: fees paid to NPR by public radio stations (almost 700 of them) for the right to broadcast particular NPR programs. These program fees account for slightly more than 50 percent of the annual budget, which for 2000, was just over $100 million. This is the largest single source of money for NPR and it comes overwhelmingly from the stations and their listeners.

The rest of the money comes from organizations (usually corporations) and foundations.

That support is known as "underwriting" and the on-air acknowledgements are called "credits." To some listeners the credits sound like plain old advertising. In fact, they aren't. They must conform to federal law which expressly forbids "advertising" on public radio stations. In fact, recently, the Federal Communications Commission (FCC) found one public radio station guilty of "broadcasting advertisements and failing to maintain its public file," after a complaint by a listener.

Reference
http://www.npr.org/yourturn/ombudsman/2001/011228.html