This article presents a longitudinal case study of an urban high school as it transitioned from one comprehensive reform model to another over a 10-year period. The study is based on qualitative interview data and quantitative data on student outcomes. Despite evidence of improved student outcomes during this reform period, the school could not meet state-mandated improvement goals because of the large proportion of students who entered with already longstanding patterns of low attendance and low achievement prior to high school. Addressing these deep structural issues will require a more systemic, rather than school-centered, focus. (Contains 5 figures, 3 tables and 1 note.)