Studies on impairment in psychologists and other mental health practitioners began appearing in the literature 30-35 years ago. Since then, research and related scholarly writings have continued to be published to more fully understand this concept and its components. In school psychology, however, little has been written regarding school psychologists' delivery of psychological services while they are impaired. This is true even though the provision of such services violates numerous ethical principles and standards of professional conduct in the ethics code of the National Association of School Psychologists and the American Psychological Association. In this article, the authors review the prevalence and incidence data regarding impairment, as well as definitional issues regarding what constitutes impairment. Ethical and legal issues associated with practicing while impaired are also discussed, followed by a discussion of assessing risk for impairment in school psychologists and the presentation of a self-administered risk assessment scale on the basis of empirical and other literature in the area of ethics and professional standards in the practice of psychology. Future directions for developing an agreed-upon definition of impairment within the field of school psychology and future directions for research on assessing and predicting impairment in school psychologists are discussed. (Contains 1 figure.)