Much of the early research on the effects of all day kindergarten had serious problems with internal and external validity due to inadequate methodological standards. This digest reviews research conducted in the 1990s. The digest discusses the academic, social, and behavioral effects of all-day kindergarten, as well as parents' and teachers' attitudes and the curriculum in all-day kindergarten classes. The digest notes research from the 1990s as showing more consistent positive academic outcomes for all children in all-day kindergarten than did earlier research. Three studies are highlighted which found social and behavioral benefits of all-day kindergarten attendance. Attitudes of parents and teachers of children enrolled in all-day kindergarten are also noted; both groups were generally satisfied with the programs and believed that all-day kindergarten better prepared children for first grade. The digest concludes by noting that all-day kindergarten seems to have many positive benefits for children and can provide them the opportunity to spend more time in active, child-initiated small-group activities. (Contains 14 references.) (KB)