Hypnosis has long demonstrated its power to facilitate various approaches to psychotherapy. Like other potent modalities, hypnosis may produce unwanted effects. Although its negative sequelae are usually mild and transient, more serious complications may occur. Recently, attention has been drawn to the powerful role of failures of dehypnosis or alerting/realerting in producing unwanted effects. Traditionally, alerting has been viewed as a relatively uncomplicated process that requires little more than the simple suggestion that the subject will return or awaken from trance, and exiting from trance has generally been considered the cessation of the phenomena suggested during induction and thereafter. Newer findings challenge these assumptions and suggest that restoring the subject to a prehypnotic baseline level of alertness is of equal or greater importance. Here, I describe the Howard Alertness Scale (HAS), with which subjects can be made aware of their baseline levels of alertness to help them understand the unique ways that their trance states differ from their normal alert states, and assess and measure their subjective perception of alertness before and after hypnosis. Furthermore, regular use of the HAS holds potential to enhance both the therapeutic alliance and the patient's sense of safety and mastery. The development and use of the HAS is discussed along with three vignettes illustrating its clinical application.