This study examines the effects of internal migration driven by severe natural disasters on host communities, and the mechanisms behind these effects, using the large influx of migrant students into Florida public schools in the aftermath of Hurricane Maria. I find significant adverse effects of the influx in the first year on existing student test scores, disciplinary problems, and student mobility that vanish entirely in the second year. I also find evidence that compensatory resource allocation within schools is an important factor driving the adverse effects of large, unexpected migrant flows on some incumbent students in the short-run.