This project focused on the collection and analysis of longitudinal student data generated by six high schools from a large urban school system in the Midwest. Two of the schools recently converted to a 4 X 4 scheduling structure, while 3 additional schools have used a block-8 scheduling structure for a number of years. One school maintains a traditional 6-period/55-minute class structure. Graduation, dropout, attendance, and retention rates were gathered several years before and after the schools' block conversions. In addition, student achievement data based on grade point averages and failure rates were also explored for this same time period. Matching data from the traditional school site were also gathered for comparative purposes. Results indicated several positive outcomes of the conversion to block scheduling structures. (Contains 46 references.) (DFR)