Ninth grade, observes Ruth Curran Neild, marks a critical juncture in American schooling. Students who manage the academic demands of the transition to high school have a high probability of graduating four years later. But those who do not-who fail to earn as many credits as they should during ninth grade-face a substantially elevated risk of dropping out of high school. Neild examines four theories about why ninth grade poses difficulties for some students. The first is that ninth grade coincides with life-course changes, such as reduced parental supervision and increased peer influence. The second is that in moving to a new school, students must break the bonds they have formed with their middle-school teachers and peers. The third is that some students are inadequately prepared for high school. The final theory is that the organization of some high schools is itself a major source of students' difficulty. Each theory, says Neild, suggests a particular type of policy response. The strongest evidence, observes Neild, points to inadequate preparation for high school and the organization of high schools. Reform efforts thus far have tended to address high school organization, with or without a focus on instructional quality or helping students to catch up on academic skills. Evaluations of these reforms, says Neild, suggest that both school organization and instructional improvement are necessary to keep ninth graders on track to graduation. Neild notes that school districts and state departments of education also are addressing the problem. In addition to supporting comprehensive school reform with a focus on ninth graders, districts have created accountability indicators of how well high schools are keeping ninth graders on track. States are helping districts to develop their capacity to maintain and analyze data on ninth-grade progress, including "early warning indicator systems" that identify students who are falling off track to graduation.