Increasing ethnic diversity and whether or not it impacts on social trust are highly debated topics. Numerous studies report a negative relationship between diversity and trust, particularly in the United States. A growing body of follow-up studies has examined the extent to which these findings can be transferred to Europe, but the results remain inconclusive. Moving beyond the discussion of the mere existence or absence of diversity effects on trust, this study is concerned with the Moderation of this relationship. It addresses the neglected role of subnational integration policies influencing the impact of diversity on trust. Empirical tests not only indicate that integration policies moderate the relationship but also suggest that the influence of policies varies substantively according to the specific policy aspect under consideration.