Abstract: A board lock device 10 holding an electrical connector 40 to a one-piece essentially planar board lock member adapted to be received in a passageway 48 extending through a connector housing 40 and a board mounting post 50 extending from a mounting face 46 thereof includes a body 12 and a pair of cantilevered beams 18 extending outwardly in a first direction in the plane from a transverse body edge 14 to free ends 24. The beams 18 defining a slot 36 therebetween. The board mounting post 50 includes a protrusion 54 extending into the passageway 48 at least at the leading end 52 thereof. The inner edges 28 of the beams 18 are adapted to enter into locking engagement with the protrusion 54 upon full insertion of the device 10 into the passageway 48 to prevent any backward movement of the device when the connector 40 is mounted to a circuit board 60.