From the Chaosium website:
A Monograph for the 1890's, 1920's, & Contemporary Adventures
This monograph reveals the real-world science of the paranormal, Parapsychology (its history and methods), how to play a parapsychologist, how to run a Call of Cthulhu campaign centered around a ghost-hunting group, and how to simulate various non-Mythos entities and psychic powers in your campaign.
Contents:
Parapsychology Exploring New Prontiers of Science
Parapsychology
Parapsychology in the Laboratory
Generating a Parapsychologist Character
Phenomena
Paradigms—Theories of the Unexplained
Ghosts and Hauntings
Investigating Poltergeists
Spiritualism and Mediumship
Psychical Research
Secrets Mankind Was Not Meant to Know
Running a Parapsychological Campaign
Ghosts: a Keeper's Guide
The Poltergeist Scenario
Mediumship Explored
Psychics
Cthulhu Rising: Cthulhu and the Psychic
Appendix A: Sinister Seeds
Appendix B: New D20 Cthulhu Psychic Feats
Appendix C: Parapsychological Literature, 1882–1930