In 2005, hurricanes Katrina and Rita forced many children to relocate across the Southeast. While schools quickly enrolled evacuees, receiving families worried about the impact of evacuees on non-evacuee students. Data from Houston and Louisiana show that, on average, the influx of evacuees moderately reduced elementary math test scores in Houston. We reject linear-in-means models of peer effects and find evidence of a highly non-linear but monotonic model--student achievement improves with high ability and worsens with low ability peers. Moreover, exposure to undisciplined evacuees increased native absenteeism and disciplinary problems, supporting a "bad apple" model in behavior.