en·theo·gen [god within; god- or spirit-facilitating] a psychoactive sacramental; a plant or chemical substance taken to occasion primary religious experience. Example: peyote cactus as used in the Native American Church.
(Click here for more on nomenclature)

Johns Hopkins / CSP Psilocybin Research
    2006 and 2008 studies of the entheogenic properties and     consequences of psilocybin

The CSP Entheogen Project Series
1. Religion and Psychoactive Sacraments: An Entheogen Chrestomathy
An on-line bibliography, with excerpts, of books, dissertations, and topical issues of journals about religion and psychoactive sacraments. Frequently augmented; currently contains over 500 references.

2. Entheogens and the Future of Religion
Anthology edited by Robert Forte

3. Psychoactive Sacramentals: Essays on Entheogens and Religion
Papers and essays from a conference co-sponsored by the Chicago Theological Seminary and CSP.

4. The Road to Eleusis
by R. Gordon Wasson, et al. Second printing with new Preface by Huston Smith and Afterword by Albert Hofmann.

5. Cleansing the Doors of Perception: The Religious Signficance of Entheogenic Plants and Chemicals
by Huston Smith.

Writings
Halluciogens and Religion: Historical To Scientific Perspectives
    Symposium XVIII at the 63rd Annual Scientific Meeting
    of the College on Problems of Drug Dependence
    R.R. Griffiths and H. deWit, Chairpersons
The Good Friday Marsh Chapel Experiment
    by Mike Young
Drugs That Shape Men's Minds
    by Aldous Huxley
Phanerothyme: A Western Approach to the Religious Use of Psychochemicals
    by Lisa Bieberman
The Psychedelic Experience - lessons from the 60s
    by Lisa Bieberman
Psychedelic Theophanies And The Religious Life
    by Huston Smith
Drugs and Mysticism
    by Walter N. Pahnke
C.G. Jung Letter Excerpt
    letter from Jung to Victor White
    about psychoactives and the unconscious
Quotations from William James, Huston Smith,
    Walter Houston Clark...
Do Entheogen-induced Mystical Experiences Boost the Immune System?
    by Thomas B. Roberts
Do Psychedelic Drugs Mimic Awakened Kundalini?
    Survey
Ecstasy for Religion
    interviews with a Benedictine monk, two Zen monks,
    and a rabbi about the use of MDMA in religious practice
Ho Chunk Meeting
    a 1987 initiation into a peyote meeting and sweat
    lodge ceremony
If I Could Change Your Mind
    by Mike Young
A Note on the Safety of Peyote when Used Religiously
    by Matthew Baggott
The Use of Music in Psychedelic (LSD) Psychotherapy
    by Helen L. Bonny and Walter N. Pahnke
The Psychedelic Experience
    Tibetan Book of the Dead (Leary, Metzner, Alpert) *
The Psychedelics and Religion
    by Walter Houston Clark *
Entheogenic Yoga
    meditation techniques
The Nitrous Oxide Philosopher
    by Atlantic Monthly article on William James *

Resources
Zeff Memorial Library Catalog
    books and papers about entheogens
Religion and Psychoactive Sacraments: An Entheogen Chrestomathy
Recommended Readings on Peyote
Society & Law

Entheogen-related Links
R. Gordon Wasson Archives
    Harvard's Wasson collection catalog *
Shamanism, Entheogens and Spirituality-Consciousness *
Disembodied Eyes
    entheogen/ethnopharmacology-related material *
Erowid Psychoactive Vaults
    documenting the complex relationship between humans
    and psychoactives *
MAPS
    Multidisciplinary Association For Psychedelic Studies *
Heffter Research Institute
    research, neuroscience, psychedelics *
The Lycaeum
    psychedelic library and community *
Sound Photosynthesis
    Archive For The Coming Millennium - audio and video
    recordings *

[* denotes an offsite source]