Abstract: An apparatus is provided for gravel packing a plurality of zones within a subterranean well. Primary sealing means are adapted for setting in casing at a position above the zones. A plurality of sets of production screens and valve means are provided, the valve means being equal in number to the zones to be packed and being carriable in the well with the primary sealing means. Zone isolation means are connected between each said set and expansible into sealing engagement with the casing. A control mandrel includes a single cross-over means for diverting gravel carrying fluid. A plurality of vertically spaced sealing means are defined on the cross-over means for successively isolating each set from the others when the cross-over means is positioned in proximity to each valve means. Valve opening means are provided on the control mandrel and are operable by longitudinal movement of the mandrel to positions for opening and closing the valve means.