This article tells the story of a group of seventh grade teachers and administrators in one Los Angeles middle school who have grappled for years with the poor reading skills of their middle school students. Discouraged by the reading scores on standardized tests and frustrated with the limits of their readers, this group struggled to improve reading comprehension in heterogeneous classrooms. The professional mandate was clear: To develop accurate comprehension assessments of their students beyond annual standardized testing, and they needed to learn to translate this knowledge into practice across the curriculum. Based on the student population and the research on reading in middle schools, teachers focused their work on vocabulary development and improving reading comprehension one word at a time. Their particular challenge assumed a greater sense of urgency because middle school provides the last chance for many students to build the sufficient reading skills necessary to succeed in demanding courses. This article describes how an assessment system that revealed the strengths and weaknesses of the readers in this school was implemented and how a research-based approach to changing classroom practice to improve reading comprehension across the curriculum was developed.