The Massachusetts Department of Elementary and Secondary Education, like other state education agencies and school districts, recognizes that the quality of instruction is a key lever to turning around low-performing schools. As part of annual monitoring of state-designated low-performing schools, the department's external monitors observe instruction in low-performing schools using Teachstone's Classroom Assessment Scoring System. The external monitors rate low-performing schools on three instructional domains: emotional support, classroom organization, and instructional support. This study examines the relationships between schoolwide instructional observation scores in these domains and schoolwide student academic achievement (measured by the percentage of students who met or exceeded expectations on state assessments) and growth in low-performing schools while taking into account what might be attributed to the schools' percentage of economically disadvantaged students and to school grade span. It found a statistically significant positive relationship between schoolwide instructional observation scores in the classroom organization domain and schoolwide student achievement in English language arts. There was no significant relationship between scores in any other domain and achievement in English language arts or between scores in any domain and achievement in math. The relationship between instructional observation scores and student achievement may be weak because achievement may be influenced by other factors, including students' prior academic achievement and the economic and social challenges their families face. The study also found statistically significant positive relationships between schoolwide instructional observation scores in each domain and schoolwide student growth in both English language arts and math. On a 7 point scale, a 1 point increase in schoolwide instructional observation score was associated with an increase in schoolwide student academic growth of 4.4 percentile points in English language arts and 5.1 percentile points in math. [For the full report, see ED607493; for the appendixes, see ED607495; and for the study snapshot, see ED607497.]