Entry titled: "Ecotage and Ecoterrorism" (286-91) (with Todd Levasseur) in the Encyclopedia of Environmental Ethics and Philosophy (Eds. J. Baird Callicott and Robert Frodeman, Detroit, Macmillan Reference, 2008).
Entry titled: "Environmentalism" (v. 2, pp. 593-98) in The Brill Dictionary of Religion, 4 vols. Editor-in-Chief, Kocku von Stuckrad (Leiden & Boston: Brill 2006). Revised and updated from the original, German "Metzler Lexikon Religion."
Entries titled: "Introduction and Reader's Guide" (encyclopedia introduction); "Bioregionalism and the North American Bioregional Congress," "Celestine Prophesy," "Conservation Biology," "Criticizing 'World Religions and Ecology," "Death and Afterlife in Jeffers and Abbey," "Deep Ecology" (with Michael Zimmerman), "Deep Ecology - Institute for," "Disney Worlds at War," "Diggers Song," "Earth First! and the Earth Liberation Front," "Jane Goodall" (with Paula Posas), "Environmental Ethics," "Hundredth Monkey" (and "Monkeys in the Field"); "Radical Environmentalism"(and "Rodney Coronado and the Animal Liberation Front"); "Restoring Eden" (with Peter Illyn); "Religious Studies and Environmental Concern," "John Seed," "Sierra Club" (with Gavin Van Horn), "Surfing" (with Glen Henning), "Snyder, Gary - and the Invention of Bioregional Spirituality and Politics," "United Nations' 'Earth Summits'," "Paul Watson and the Sea Shepherd Conservation Society" (with Steve Best); in The Encyclopedia of Religion and Nature. (Editor-in-Chief, Bron Taylor, London & NY: Continuum 2005). (Approximately 80,000 words)
Entries titled: "Deep Ecology" (180-82) "John Muir" (424-25), "Nature Religion" (454-56), "Neo-Paganism" (458-60), "New Age Religion" (460-61), "Sojourners Fellowship" (633-34); in The Encyclopedia of American Religious History (Facts on File, revised edition, 2001).
Entries entitled: "Nature Religion" (484-85) and "Deep Ecology" (182-83); in Contemporary American Religion. Ed. Wade Clark Roof (New York: Macmillan, 2000).
Entries titled: "Deep Ecology," (180-81), "John Muir," "Nature Religion," "Neo-Paganism," "New Age Religion," "Sojourners Fellowship"; in The Encyclopedia of American Religious History. (Facts on File, 1996).
Entries entitled: "Environmentalism" (pp. 140-44) and "Earth First!" (pp. 130-133); in Encyclopedia of Millennial Movements. Ed. Richard Landes (New York & London: Routledge, 2000).
Entries entitled: "Affirmative Action" (Part I, pp. 15-17) and "Sustainability" (Part II, p. 244); in Dictionary of American History (supplement). Eds. Robert Ferrell and Joan Hoff (Lakeville, Connecticut: Scribner's American Reference Publishing Company, 1996).
Entries titled: "Radical Environmentalism" (539-40), "Environmental Movements: Less Affluent Nations" (254-55), "Eco-spirituality," (204-05). "Wildlands Project" (204-05); in Conservation and Environmentalism: An Encyclopedia. Ed. Robert Paehlke (NY: Garland, 1995).