A stand-alone chamber or multi-chamber inhalation system has at least two alternative vaporized test liquid supply systems for passive or self-administered delivery of vaporized test fluid and air to one or more test chambers, which can be passive or restraint chambers, based on operator selection of delivery on and off times in a passive mode or actuation of an actuator in the chamber by a test animal in a self-administered mode. In one case, a multiple inhalation chamber system has two or more separate test fluid delivery systems and provides options for selective passive uniform drug delivery to multiple chambers or selective delivery of two or more different drugs to different groups of chambers from different delivery systems so that two different drugs or different concentrations of delivered drugs can be tested simultaneously.