In this study, we examined the role of morphology, an important yet largely understudied source of difficulty, in reading ability among 7th grade students in one junior high school in the southwestern United States. We sought to find out how much variance in reading ability is accounted for by these students' morphological knowledge, and whether skilled readers do in fact have higher levels of morphological knowledge than less skilled student peers. We found that students' sensitivity to the morphological structure of words accounted for 18% of the variance in these students' reading performance. We further found that skilled readers had a significantly higher level of sensitivity to the structure of words than did less skilled readers. In light of these findings, we offer recommendations for interpreting and using the results obtained to better understand and scaffold students' morphological knowledge, with the goal of helping promote students' vocabulary growth and reading comprehension performance.