School learning starts with school attendance. Students need to be in school to receive instruction and learn from their teachers and peers. When schools have high rates of poor attendance, their academic achievement levels suffer. Ninth grade is a critical juncture that comes with increased student autonomy -- and new pitfalls, including the potential for disengagement. Students are often held to increasing academic expectations that put more of the responsibility in their own hands. If students react by disengaging from school, their academic futures could be in danger. The School District of Philadelphia (SDP) found that the stronger a student's ninth grade attendance, the more likely that he or she will graduate on time. But in a long school year, when should schools start paying attention to student attendance? In this report, the authors study attendance patterns of first-time SDP ninth graders during the 2015-16 and 2016-17 school years. They examine the spread of overall attendance rates in these two student cohorts, patterns over the course of their ninth grade year, and how those patterns differ for students with different levels of academic achievement.