We study early grade teacher attendance in a nationally representative sample of public primary schools in Tanzania. We document high and costly levels of absence: during unannounced school visits, only 38 percent of teachers are observed to be actively teaching in the classroom. We find that an experimental incentive program that provided test-based performance rewards improved classroom attendance and teaching among eligible early grade teachers, although it did not explicitly incentivize attendance. Using panel regressions across the full sample, we find that teacher attendance is positively associated with the probability of school inspections and that classroom attendance and teaching activity is substantially higher among female teachers. Traditional incentives such as school infrastructure quality and salary level do not correlate with attendance.