Communities with high immigrant populations have less crime

A recent article in the Dallas Morning News reported that crime was lower in communities with high immigrant populations, lower than would be predicted by socioeconomic status, a co-variate with crime. This in paragraphs 21-23 comparing Dallas and surrounding cities:

Most cities have violent crime rates that are in line with similar communities around the country. But four area cities – Irving, Denton, Garland and Grand Prairie – had much lower violent crime rates than their socioeconomic statuses would suggest.
While many factors could account for the lower crime rates, recent research might explain at least some of Irving's performance.
High immigration correlates with lower crime rates. Irving has the greatest proportion of foreign-born people among cities with at least 65,000 residents outside the West and East coasts. About a third of the city's population was born elsewhere.
And that runs counter to the common assumption that associates immigrants with crime, said Robert Sampson, professor of sociology at Harvard University. "The data just don't bear this out in any way."
Dr. Sampson points to several reasons why immigration correlates with lower crime rates. Immigrants, he said, often are motivated to improve their lives. Many immigrant families have more traditional family structures. And in many cities, immigrants have improved the economies of their communities.

During the posts on illegal immigration, the self suppressed finding of a sociology professor's finding of a negative effect of diversity on community health was a topic on the old Asymmetric Information blog. Moreover it seems a generally held idea.