In this paper, we introduce explicit rate adjustment (ERA), a new multi-rate multicast congestion control (MR-MCC) algorithm. Via ERA, the receiver explicitly adjusts its reception rate according to the network conditions using the TCP throughput equation and packet-pair probe. The design goals are responsiveness, efficiency in network utilization, scalability and fairness (including inter-protocol fairness, intra-protocol fairness, intra-session fairness and TCP-friendliness) as well as simple implementation. We have built ERA into a network simulator (ns2) and demonstrate via simulations that the goals are reached.