There are only a handful of formal studies that examined the impact of changes in school starting time on student learning and behavior. The Center for Applied Research and Educational Improvement (CAREI) at the University of Minnesota is a leader in this research and identified the impact of changes in school starting times across the school, community and family contexts. Most of the research on extended school days examined the impact in elementary and middle school settings. Only recently have researchers began to look at the impact of extended days on high schools. The following factors, drawn from the literature, summarize things to consider when thinking about extending the school day: (1) Impact of school start time within the school context; (2) Impact of school start time on the community; (3) Impact of school start time on families; and (4) Impact of school start time on students. Several school districts from New York to California to Alaska have discussed extending the day, however, no more than a few dozen have implemented such a plan. When implemented little data has been gathered on the impact of change. When considering an extended day, whether an early start, later start or staggered start times including flexible scheduling, schools must consider the impact on families, student employment and other factors. For many schools these considerations may carry greater weight than educational benefits. (Contains 9 online resources.)