An injection device including an accommodating device for a substance to be delivered, e.g. a vial or ampoule holder, which is insertable into and can be displaced relative to the injection device or a part thereof; an adjusting element for adjusting a dose to be administered from the injection device, which element is inserted in the injection device; and a coupling element for coupling the accommodating device to the adjusting element so that the adjusting element is at least partially moved out from the injection device when the accommodating device is inserted. A method for preparing an injection device using a dual chamber vial or ampoule to administer a substance, wherein the method involves using an adjusting device which is released, extended or pushed out from the injection device not before or after the substance to be administered from dual chamber vial or ampoule is mixed.