The mandates of the federal No Child Left Behind Law, including the threat of closing a school for underperformance, have led to multiple public school turnaround attempts. Because turnaround is a relatively new area of focus in education, there is limited research on what does and does not work, and even the definition of turnaround is a work in progress. The research that is available is almost exclusively from the public school sector. This article gives some history and context for school turnarounds currently taking place in the United States and describes the turnaround of a Catholic, inner-city high school in the Archdiocese of Boston. The school, Cristo Rey Boston High School--formerly North Cambridge Catholic High School--has a history spanning nearly 100 years. Unlike a public school, North Cambridge Catholic High School was not subject to closure or takeover for consistently poor student performance on standardized tests. Instead, the principal and his faculty were driven by their own desire to improve the quality of education they were offering their students. (Contains 3 tables and 4 figures.)