CDC light-trap collections and larval dipping conducted during 2004 and 2005 revealed Culex coronator firmly entrenched in 10 counties in central and south Mississippi. A total of 3,307 specimens (2,200 adults, 1,107 larvae) of Cx. coronator have been collected in Mississippi. Notes on breeding sites and seasonality are presented and discussed. It is likely that the Mississippi population of Cx. coronator is contiguous with the one previously known from southern Texas, because specimens have been collected in Harris County, TX over the last few years, and were also found in Louisiana in 2004. Establishment of this population of a nonnative mosquito in Mississippi reveals how apparently easy it is for such events to happen.