Many school districts have turned attention to school grade configuration as a way to ease student transitions and improve academic performance, however the research base supporting such reforms is limited. Little attention has been given to how and to what degree school attachment influences the relationship between schools' middle level grade configuration and student achievement. This multilevel, quantitative study used data from the Early Childhood Longitudinal Study, Kindergarten Class of 1998-1999 (ECLS-K) to investigate school attachment and its relationship to grade configuration and achievement. The authors found that school attachment predicts a significant degree of change in student achievement and call for reformers to be cautious about seeking to improve student outcomes through such structural changes as new grade configurations (i.e. K-8). (Contains 2 figures and 5 notes.)