A clip for mounting an elongated trim strip on ends of ceiling grid runners, having a right angle configuration with two intersecting legs, one leg adapted to laterally abut an end of a grid runner and the other being adapted to engage the trim strip, said other leg having oppositely extending upper and lower grips for reception into upper and lower opposing channels of the trim strip, the grips being relatively moveable, and a toggle arrangement for moving said grips away from one another, when retracted, the grips being capable of passing between the opposed channels, the toggle arrangement selectively maintaining said grips in an extended position to frictionally lock onto the opposed channels of the trim strip.