(57) An electrical connector system is disclosed and includes a plug connector assembly (20) mateable with a right angle header connector assembly (22). The plug connector assembly includes a plurality of terminal-receiving modules (34) juxtaposed in a nested array in a cavity (42) in a housing (28). The right angle header connector assembly includes a plurality of generally flat terminal modules (94) nested within a cavity (96) in a housing (90) in a side-by-side relationship. Each terminal module of the header connector assembly includes a plurality of generally coplanar flat terminals (102) surrounded and maintained in a desire array by an overmolded module encasement (110). The terminals have opposite terminal portions projecting from the encasement (98, 100). Both the plug connector assembly and the header connector assembly are shielded connectors and each include a shield (30, 32, 92) about a substantial portion of the respective connector assembly. The connector assemblies are held in mated condition by latches (76) which are actuated by a cover (26) mounted for relative movement about the plug connector assembly.