A needle safety device (1) has an outer tube (10) within which a syringe barrel (2) is slideably receivable. A collar (14) in the outer tube (10) is moveable relative thereto and rotatably attachable to the distal end of the barrel (2). A force member (16) biases the outer tube (10) in a distal direction. A track (S) is formed in the inner surface of the outer tube (10). A pin (18) extending radially outwardly from the collar (14) slidingly engages the track (S). In a staging position, the barrel is inspectable. In a pre-injection position, the cannula extends a first length beyond the outer tube. In a full-insertion position, the cannula extends a second length greater than the first length beyond the outer tube. In a locked position, the cannula is entirely within the outer tube.