Side air-bag with internal tether

A side air-bag formed from two layers of fabric includes an internal tether extending from a fold-line in a region of the air-bag configured to receive a gas generator to a point on one of the layers of fabric. The distance around the periphery of the air-bag between the ends of the tether is greater in one direction than in the other direction. The length of the tether is less than the shorter of the two distances. The tether serves to assist in guiding the air-bag, on inflation, so that it extends forwardly from a vehicle seat to lie adjacent an occupant of the vehicle seat.