Harvard University sociologist Robert Sampson examined crime and immigration in Chicago in 180 neighborhoods of varying levels of integration. He also analyzed recent data from police records and the U.S. Census for all communities in Chicago.

Based on assumptions that immigrants are more likely to commit crimes and settle in poor, disorganized communities, prevailing wisdom holds that the concentration of immigrants and an influx of foreigners drive up crime rates, Sampson said.

However, Sampson showed that concentrated immigration predicts lower rates of violence across communities in Chicago, with the relationship strongest in poor neighborhoods.

"Not only does immigration appear to be 'protective' against violence in poverty areas, violence was significantly lower among Mexican-Americans compared to blacks and whites," Sampson said in a statement.

The study, published in the winter issue of Contexts magazine, found that first-generation immigrants were 45 percent less likely to commit violence than third-generation Americans.