Abstract: For a modular pickup bed cover system having a plurality of rigid transverse panels which slidingly fit into longitudinal channels fixed along bed side walls, interpanel latching is provided by a transverse, channel-shaped first latching member fixed across rearward ends of all except the rearmost panel and a matching, transverse, angle-shaped second latching member fixed across forward ends of all except the forwardmost panel. Fixed across the rear panel of each panel pair in panel abutment regions is an elastomeric seal. As each pair of panels is latched together, upon installation thereof into the truck bed side channels by pivotally fitting the rearward panel angle member into the forward panel channel member, the seals are compressed a preselected amount assuring weathertight interpanel sealing. Shaped end regions of the latching members cause transverse panel alignment during latching.