Of all the mass media, radio is the most abundant, both in terms of the number of radio stations in operation and the number of radio receivers in use. Unfortunately, given the dynamics of a competitive market and the Federal Communications Commission's reluctance to interfere with a licensee's discretion in the choice of format, format duplication is inevitable. At present, format diversity reflects divergent interests and tastes only as marketplace forces dictate. Neither has format diversity been subject to regulatory scrutiny. Prodiversity policy focuses on nonentertainment programing and is intended to achieve only intramedia diversity. To foster pluralistic programing--and to avoid excessive sameness among formats--unprofitable formats need to be protected in much the same way nonrenumerative public affairs programing on television is protected. Specifically, stations serving large and demographically appealing taste communities would bid for the right to a frequency, while stations servicing less appealing taste communities would be subsidized (negative bidding). (HOD)