This paper proposes a novel, simple reactive power control strategy for the active load balancer (ALB) in three-phase four-wire distribution systems. The proposed reactive power control strategy is applicable for adjustment of the source-side power factor under the balanced load condition. Only DC capacitor voltage control is used in the proposed control strategy. Therefore, the calculation blocks of the active and reactive components of the load currents are not necessary. The authors, thus, offer the simplest control strategy to control reactive power under the balanced load condition on three-phase four-wire distribution feeders. The basic principle of DC capacitor voltage control based reactive power control strategy is discussed in detail, and then confirmed by digital computer simulation. A prototype experimental system was constructed and tested. Experimental results demonstrate that balanced source currents with reactive power control are achieved on three-phase four-wire distribution feeders. These experimental results also demonstrate that controlling the reactive power reduces the required power rating of the ALB compared to that of the existing control strategy, which achieves balanced source currents with unity power factor.