We examined the population genetic structure of an extremely successful invasive wasp, Polistes dominulus. Although successful biological invasions of social insects have been associated with genetic bottlenecks, our research uncovered an unexpected level of genetic diversity in the northeastern U.S. invasion population. Compared with a previously studied European sample, the northeastern U.S. invasion population shows no significant reduction in gene diversity and no trace of a genetic bottleneck in the putative “introduction population.” We identified multiple private microsatellite alleles in both Massachusetts and New York, which strongly suggests that the northeastern U.S. P. dominulus population arose from at least two independent introductions. Although a genetic bottleneck may enhance invasion success for some social insects, genetic and geographical data on this successful invader suggest that this wasp may represent the converse. Our results support immediate identification of genetic diversity in an invasion population before the occurrence of secondary introductions as an essential part of managing and controlling invasive species.