Laboratory tests of extrasensory perception have been going on for over 50 years, attracting international interest within the scientific community. Some scientists believe that these studies are well-conducted, and that positive results obtained support the existence of ESP. In contrast, critics have argued that there are serious methodological errors in such experiemnts and that their results should be ignored. However, both sides agree that there are many ways in which errors may arise in ESP studies and that anyone involved in conducting or assessing such experiments should be aware of these potential pitfalls. Recommendations and commentary on safeguarding the testing of extrasensory perception has previously been scattered throughout an extensive literature. This book brings together this material and discusses the issues, providing clear guidelines in a checklist format to aid researchers to carry out and recognize testing in this area of science. This is the second volume in a series on "Guidelines for Parapsychological Research" edited by Richard Wiseman, co-author of this title and of the first text in the series, "Guidelines for Testing Psychic Claimants".