Distributed Flexible AC Transmission System (D-FACTS) devices offer many potential benefits to power system operations. This paper illustrates the flexibility of control that is achievable with D-FACTS devices. The impact of installing D-FACTS devices is examined by studying the sensitivities of power system quantities such as voltage magnitude, voltage angle, bus power injections, line power flows, and real power losses with respect to line impedance. Sensitivities enable us to quantify the amount of control D-FACTS devices offer to the system. Independently controllable lines are selected for power flow control, and appropriate locations to install D-FACTS devices for line flow control are determined. Then, D-FACTS device settings are selected to achieve desired line flow objectives.