Consider stations sharing a single communications channel. Each station has a buffer of length one. If the arrival rate of station is ri, then is shown to be an upper bound (over all policies) on the throughput of the channel. Moreover, an optimal policy always exists and is stationary and periodic. The throughput of two policies, the random-policy, and the golden-ratio policy, are analyzed for a finite and infinite number of stations. The latter is shown to approach a limit which is within at least 98.4 percent of the upper bound.