This article examines recent research on full- and extended-day kindergarten programs held every day. Preceding the review are general comments concerning methodological concerns and a description of essential features of the literature. The review is organized in terms of specific end-of-year effects because administrators seeking justification for local programs will have particular goals in mind. Effects reviewed include: basic academic skills and social, emotional, and developmental considerations, such as fatigue, staff reaction, parent reaction, attendance, and socioeconomic and ability level differences. Also examined are studies concerning support service referrals and grade retentions; follow-up studies; financial considerations; enrollment benefits; and time schedules. Issues implicit in the literature are discussed; these include the new role of kindergarten for the academically weaker child and the questionable value of increasing instructional time. It is argued that the field needs to accept basic research prerequisites and minimum reporting standards. A list of 56 references concludes the document. (RH)