Reasons for the present emphasis on all-year operation of schools differ from those prevailing 30-40 years ago. During the depression emphasis was on economy. Recently, a more sensible reason for an extended school year is coming into focus--the year-round school has educational value. It is not just something to be considered in order to save money, though that certainly is one of the criteria. The year-round operation of the public schools is necessary for meeting the educational needs of an urban society. After a lengthy review of the research on and practice with the extended school year, the author presents extensive findings in favor of the extended school year. He addresses such areas of concern as academic achievement, remedial programs, graduation rates, mental health, student maturity, student social needs, handicapped children, and college admission. (Author/IRT)