Abstract: A side-pocket mandrel for supporting a flow control device such as a gas lift valve along a well flow conductor and a method of operating same. The mandrel is connectible with pipe sections to form an integral length of a flow conductor and has a central bore communicating with the bore of the flow conductor, an orienting sleeve along an end portion of the mandrel, a side-pocket portion communicating with the main bore, a side-pocket landing nipple in the side pocket portion communicating with side ports in the mandrel along the landing nipple, a sliding sleeve valve disposed in the landing nipple for controlling communication through the side ports opening into the landing nipple, and a flow control device such as a gas lift valve releasably lockable in the sliding sleeve valve.