We study the effect that a series of islamist terrorist attacks across europe in 2004–2005 had on the integration of muslim immigrants. Using unique panel data that oversamples immigrants in the netherlands, we show that, shortly after the attacks, muslim immigrants’ attitudes toward integration worsened significantly compared to those of non-muslim immigrants, with no evidence of a negative trend in the attitudes of muslims prior to the attacks. While, in particular, low-educated muslims became more geographically segregated and unemployed after the attacks, high-educated muslims were affected most negatively in terms of their perceived integration. This decline in perceived integration is associated with a higher intention to permanently ...