The canonical (ok, so witchcraft has no canon, but close) basic study of modern Witchcraft/Paganism. Margot Adler set out to do an anthropological study of pagans in the late 1970's. This volume covers the history of "neopaganism" and basic sketches of many of the major paths/traditions. Interviews, historical research, and a lively writing style combine in a solid overview of the subject.
An excellent book for anyone curious about neopagan traditions, and essential reading for every pagan, wiccan and witch. Of special interest is the chapter on becoming a pagan, which tends to provoke a two- or three- week period of wandering around muttering "So THAT'S what I am" in new pagans. *grin*