The analysis of the planning for an implementation of an alternative high school in a large urban school system is the focus of this study. Interview data are used. This investigation draws on, and compliments, the previous literature on implementation. While most of the earlier studies look at failures, this one is based on an instance of successful implementation. The study identifies four factors that may account for successful implementation, the intent being to partially account for that success and to provide some clues to what program administrators can do to make it more likely that new programs will get fair trials in the schools. The school was formed from the top-down providing legitimacy within the larger system and a measure of homogeneity. A large amount of lead time allows the faculty to develop personal ties and to share goals and values pertaining to the new school. Staff commitment to the school is fostered by mutual shaping by principal and teachers. Internal and external harmony is facilitated by stacking-the-deck. The strategy utilized by City Wide High School also has some negative features. The approach seems to reduce the chances for dissemination of the innovation within the school system. The large amount of lead time and the stacked deck, in particular, cannot be duplicated every time. Despite its shortcomings, City Wide High provides an alternative, and it is surviving. (Author/AM)