Excessive school absence disrupts learning and is a strong predictor of premature school dropout. School-aged children with asthma are absent more often compared to their healthy peers without asthma; yet, the causes are inadequately documented. We sought to determine the difference in mean absence days between children with and without asthma, the relationship between asthma severity and missed days from school, and if incident absences were due to asthma in a predominantly African American urban school district in the Midwestern United States. A cross-sectional analysis was conducted of 9014 students (grades K-12) followed for absenteeism over the 2002-2003 academic year. A subset of 543 students with asthma was assessed for asthma severity and cause of absence. Those with asthma (9.7% of students) were absent (mean = 9.2 days) approximately 1.5 more days compared to those without asthma (mean = 7.9 days) (p = .006). In the analysis comparing asthma severity and absenteeism, after adjusting for demographic variables and enrollment time, mean days absent increased with increasing asthma severity level: mild intermittent (mean = 8.5 days), mild persistent (mean = 11.3 days), moderate persistent (mean = 10.3 days), and severe persistent (mean = 11.6 days) (p = .001). Out of 1537 tracked absences that resulted from illness, 478 (31%) were due specifically to asthma-related symptoms. Children with asthma are absent from school more often compared to their healthy peers and this appears to be driven by the underlying severity of symptoms. (J Sch Health. 2006;76(1):18-24).