We exploit rules of class formation to identify the causal effect of increasing the number of immigrants in a classroom on natives test scores, keeping class size constant (Pure Composition Effect). We explain why this is a relevant policy parameter although it has been neglected so far. We show...

Recent immigrants tend to locate in ethnic ‘enclaves’ within metropolitan areas. The economic consequence of living in such enclaves is still an unresolved issue. We use an immigrant policy initiative in Sweden, when government authorities distributed refugee immigrants across locales in a...