A pin and grommet fastener includes a grommet that defines a central aperture and includes at least two adjacent longitudinally extending leg members that each include a frame, a knuckle and a tether. The knuckle is connected to the frame at a hinge region that is designed to permit the knuckle to move relative to the frame. The tether connects the knuckle to a base surface of grommet in order to limit movement of the knuckle relative to the frame. The fastener includes a pin that has a first locking member to retain the pin in a first position relative to the grommet in which the longitudinally extending leg members are in a laterally unexpanded state. The pin also has a second locking member to retain the pin in a second position relative to the grommet in which the longitudinally extending leg members are in a laterally expanded state.