Over the past several years, student growth and growth models have received a lot of attention, in both the charter school sector and the larger education community, as an important indicator for measuring school quality. Educators and policy makers alike have been won over by the argument that because measures of student growth examine the changes in performance of the same students over time, they tell us more about how well schools are educating our nation’s students than do measures of student achievement, or status. Several states now have “federally approved” growth measures as part of their statewide accountability frameworks, but the methods for computing student growth are many and each method tells something different. Understanding exactly what the data is telling is critical if growth models are to have value in evaluating the quality of a given school.