Yes it will fold flat, that is the way it comes in the box. The 3 dividers are each held in place on one side by the structure and then can be swung around to form a divider and held in that place by 4 velcro (hook and loop) fasteners (2 at top and 2 at bottom). So the size of the boxes can be changed to meet your needs. It has handles at each short side. The organiser pulls straight out of the trunk if you want or can be moved forward to the back seats. Quite a flexible design.Wow! I really like the trunk organizer. I am going to my dealer to see if I can get one ordered. The one I am using is only two compartments and doesn't extend to the sides. Does this one fold flat if you don't want to use it but keep it available in the trunk?