A suture sleeve for securing an implantable lead to body tissue has a lumen that receives the lead and that includes a locking arrangement that secures the sleeve at a selected position along the lead. The locking arrangement provides the suture sleeve with three modes of operation. In the first mode, the size of the lumen exceeds the diameter of the lead, such that the suture sleeve is easily movable along the lead. In the second mode, the size of at least a portion of the lumen is reduced, causing the sleeve to apply pressure to the lead so that relative movement between the sleeve and the lead is prevented. In the third mode, the pressure is temporarily released, allowing the sleeve to again be movable along the lead.