The authors claim that assessing spelling in Grades 3-12 has utility. They base their claim on data from 875,040 students in Grades 3-12 in 52,923 classes in 840 Florida schools who took the Reading Comprehension, Maze, and Word Analysis spelling portions of the "Florida Assessments for Instruction in Reading" during the 2009-2010 school year. The importance of instruction to spelling ability was evident in (a) the large intraclass correlations at the class relative to the school level, (b) the greater variability in spelling at the class level rather than at the student level, (c) the greater role of demographics at the class level compared to the student level, and (d) the role of high ability spelling classrooms compared to low ability spelling classrooms in differentiating Reading Comprehension and Maze performance. Growth in spelling was evident in the elementary grades but stagnant above Grade 7. The authors conclude with the hope that secondary teachers will include spelling instruction as part of their goal to engage students in reading for understanding. (Contains 5 tables and 1 figure.)