The apparatus used for testing is described, and the psychophysiological foundations of polygraph testing are discussed. The extent of use of polygraphs by the public and private sectors is delineated, and State licensure and certification requirements are reviewed. A review of research into polygraph validity and reliability and factors affecting it covers laboratory, criminal case, and employee studies. Legal issues examined include the right to privacy, the right to avoid self-incrimination, civil rights, and admissibility of polygraph evidence. The legal status of polygraph screening by employers also is discussed. Finally pros and cons of polygraph testing are presented in the context of legal, moral, and reliability/validity issues. It is concluded that the polygraph technique is valid and reliable when quality instrumentation is used by well-trained and educated examiners of impeccable character. It provides a source of data that is as accurate as such legally admissible evidence as expert and eyewitness testimony and psychiatric and psychological findings. It also provides an effective and relatively inexpensive method for employment screening and reduction of internal theft. 16 references.