An aircraft comprises a wing, a wing tip device at the tip of the wing and an actuator. The actuator is arranged to effect movement of the wing tip device between a flight configuration for use during flight and a ground configuration in which the wing tip device is moved away from the flight configuration such that the span of the aircraft is reduced. The aircraft comprises a carriage guide, such as a rail, fixed relative to the wing, and a carriage arranged to move along the carriage guide as the wing tip device moves between the flight and ground configurations. The wing tip device is fixed relative to the carriage such that the path of the wing tip device, during movement of the wing tip device, between the flight and the ground configurations, is defined by the shape of the carriage guide.