We can't say scientifically if this shampoo/conditioner causes hair growth, but there are many in the hair industry who claim that argan oil has the ability to help with hair loss, and cause regrowth. It could be because you're getting the oils needed to give your hair the ability to return to growing in its natural state again, as suggested by Ally in her comment below. One thing that argan oil is very well known for is repairing and strengthening hair, which will cause it to look fuller and thicker. Be sure to avoid styling products that contain harsh chemicals, such as sulfates, sodium chloride and parabens, as they will be counter-productive in your efforts to keep your hair healthy and full. This shampoo/conditioner set contains none of those ingredients, and the argan oil within it will certainly help make your hair healthier and fuller.