The Communications Act requires the FCC to auction rights to use the electromagnetic spectrum so as to recover, for the public, a portion of the value of the public spectrum resource and avoid the unjust enrichment of licensees. This use of the venerable common law doctrine of unjust enrichment is unique in the U.S. Code. Its inclusion in the alien medium of communications law raises intriguing questions about how spectrum access should be valued and how fairness in the distribution of access rights can be achieved. Complaints that there has been unjust enrichment or a spectrum giveaway are common at the FCC. These claims about spectrum equity slow the FCC's efforts to give parties the rights to use old licenses for new purposes. If unlicensed spectrum users come to gain protection from interference, or the right to cause interference, claims about equity will crop up here too. It is both desirable and necessary for policymakers to address these claims with a clearer understanding of spectrum value. This essay examines various meanings and metrics of spectrum equity, highlighting the importance of interference entitlements to the value of spectrum.