Psychic phenomena, recorded throughout human history, remained a mystery or a matter of faith rather than a subject of serious study until scientists began to investigate them roughly a century and a half ago. Systematic experimentation began with the work of J.B. Rhine at Duke University, resulting in the publication of Extra-Sensory Perception (1934) followed by Extra-Sensory Perception After Sixty Years (1940). Rhine and researchers who came after him struggled to present sufficient evidence to gain scientific credibility for the existence of extrasensory abilities. Yet despite tight experimental controls and numerous significant results the subject remains controversial. Parapsychologists argue that the impasse is not due to a lack of evidence but to the challenge their claims pose to the worldview of science in general. This comprehensive introduction to parapsychology, written by one of the most notable investigators, provides an overview of its concepts, theories and methods, and its controversies, problems and prospects.