Tough (1967, 1971), building onthe work of Houle (1961), who provided the first comprehensive descrip-tion of self-directed learning as a form of study. Tough studied and describedthe self-planned learning projects of sixty-six Canadians. The uncoveringand documenting of this type of learning—learning that is widespread, thatoccurs as part of adults’ everyday life, and that is systematic yet does notdepend on an instructor or a classroom—generated one of the major thrustsof research in the field of adult education