A recent international survey discovered that clinicians who use hypnosis in their practice rarely assess the hypnotizability of their patients or clients. This contrasts sharply with the practice in laboratory research. One reason offered for this discrepancy is that hypnotizability does not strongly predict clinical outcome. But a comparison of this relationship with similar correlations in other domains shows that this criticism is misleading-especially when the treatment capitalizes on the alterations in perception, memory, and voluntary control that characterize the domain of hypnosis. Routine assessment of hypnotizability improves clinical practice by enabling clinicians to select patients for whom hypnosis is appropriate; and it improves clinical research by providing important information about the mechanisms underlying hypnotic effects.