A device is provided for controlling the closing movement of a sliding door. The device comprises a housing (10) containing a spring (11) which is actuable to provide a pulling force to the closing movement of the door. The housing (10) also contains a damper (12) which is actuable to impart a damped resistive force to the closing movement of the door. Incorporated within the device is a gearing mechanism for converting the rate of the closing movement of the door into two or more rates of actuation of the damper over at least part of the door's travel.