Danny Pinkus points me to this post which points to a new paper examing public attitudes in Europe and the United States. They find that though overall attitudes toward immigration don't vary much on either side of the Atlantic, Europeans tend to be less positively inclined toward cultural or religious diversity. Check the post & paper for details. To the left is a scatterplot which John Sides kindly produced upon request. It is interesting to point out that Americans and the French both come out as the least fixated on religious homogeneity despite the fact that among Western societies they come out at opposite ends in terms of secularism.