An airbag module having a cushion with a compression-deployed volume. The module includes an inflator which produces a quantity of inflation gas. This gas inflates only a first volume of the cushion, which is positioned to protect a first portion of a passenger's body. Compression of the first volume by the passenger forces the gas from the first volume into a second volume, to thus inflate the second volume. The second volume is positioned to protect a second portion of the passenger's body. The initial quantity of inflation gas is thus reused, reducing the amount of gas required. This in turn reduces the size and cost of the inflator. The module is preferred for side impact protection, and a fold arrangement suited to accurate deployment is provided. The folded cushion may be secured to the inflator by a frangible film wrap, eliminating the need for an exterior housing. The module is preferably mounted upon the side of the passenger seat back.