Over the past decade, New York City's high school graduation rate has risen dramatically, yet roughly a quarter of each entering 9th-grade class still does not graduate on time. Some of these students permanently drop out in their first four years, but a much larger percentage actually stay enrolled (or reenroll after temporarily leaving school) and continue working toward their diploma. The report, the first in the Equity, Access, and Diversity series, focuses on these "persisting" students. They not only are a large group (about one in five--or more than 12,000 students per entering class), they are also particularly vulnerable. Yet, the fact that persisting students continue to have a connection to the education system offers meaningful opportunities to intervene and provide them with support. The report uses mixed methods to explore who persisting students are, how they fall off track, which schools they attend, and the supports that students and educators see as most important for helping persisting students succeed. Drawing on these findings, the report highlights the need to: (1) Identify at-risk students early--and intervene early: This study adds to a growing body of evidence highlighting the need for more scrutiny of students' middle school performance and experiences. Furthermore, the findings underscore the importance of sustained attention to students' personal and family lives to better identify those who are most at risk. While persisting students are often chronically absent in early high school, they generally do not stop coming entirely. This means it is possible to work with them; (2) Be more strategic about student placement: We found that a quarter of persisting students were enrolled in the same 20 schools during their 9th grade year (of more than 400 high schools citywide). A significant proportion of persisting students end up transferring into an alternative school--indeed, this is one of the primary systemic interventions for students who fall behind. However, interviews with students and educators suggest that decisions about when and where to move persisting students sometimes occur in an ad hoc fashion. Providing educators with more information and clearer guidelines about available options might improve the process for assessing students' needs and identifying appropriate interventions; and (3) Tailor interventions to students' needs: Persisting students enter their fifth year of high school with a wide range of academic needs. About a quarter are only marginally behind--they typically have enough credits to graduate, but haven't passed all the required Regents exams. About 44 percent are moderately behind (lacking both credits and Regents exams), and 30 percent are drastically behind (they still have to complete several years of coursework and have only passed one Regents exam, on average). Given their varying needs, students in these three groups are likely to benefit from different types of intervention. The report highlights a number of important areas for future research. These include studies examining how traditional high schools identify and support vulnerable students; studies examining the distribution of struggling students across schools, and how systems for placing and transferring students might be improved; and studies examining which educational settings are most effective for different types of persisting students. [For the summary, see ED591645. For the technical appendices, see ED591646.]