We examine the prevalence, distribution, and effects of late teacher hiring in a large urban school district. Nearly one in five new teachers in the district is hired after the start of the school year. Low-achieving schools serving low-income students struggle the most with staffing classrooms on time. Late hiring has serious consequences for student achievement. Students in classrooms with teachers hired after the start of the school year do substantially worse than their peers with other newly hired teachers (0.058 SD in math, 0.044 SD in reading). We find some evidence that these effects reflect negative selection in the teacher labor market, particularly in middle school math. However, we also find strong evidence that late hiring has temporary disruption effects on achievement that do not persist beyond a teacher’s first year in the district. Teachers who are hired late also leave their schools and the district at much greater rates than their peers who are hired on time.
