A long outstanding problem in magnetospheric physics is the cause of magnetic storms. Traditionally, the ring current buildup is attributed to the accumulated effects of energetic magnetospheric particles injected by frequent occurrence of magnetospheric substorms. Recent studies, however, suggest enhanced magnetospheric convection as the sole cause. We employ for the first time the relatively new remote-sensing technique based on global monitoring of energetic neutral atom (ENA) emissions to address this controversy. The ENA observations were combined with the ground-based magnetic indices for substrom activity and ring-current development as well as with the global monitor of magnetospheric convection in the ionosphere by the network of SuperDARN radars. The ring current is shown to intensify during enhanced convection without substrom occurrence and during a substorm with a reduction in convection. Therefore, both substorms and enhanced convection contribute to the buildup of the storm-time ring current. ¿ 2001 American Geophysical Union