The invasive nematode Anguillicoloides crassus parasitizes the swim bladder of eels, including that of the American eel, Anguilla rostrata. Despite its potential devastating effects on eel populations, however, its intermediate host(s) is/are unknown in North America. The goal of this study was to determine whether An. crassus could infect copepods collected in the wild from the Goose Creek Reservoir in South Carolina, U.S.A., where An. crassus is known to occur. Cyclopoid copepods, identified morphologically as belonging to the Acanthocyclops robustus–americanus–vernalis species complex, were successfully experimentally infected by second-stage larvae (L₂s) of An. crassus from eels captured in South Carolina, U.S.A. One infected copepod was identified as Ac. americanus via sequencing of a 251-base pair (bp) portion of mitochondrial cytochrome oxidase I DNA. For each infection experiment, 30 to 60 copepods were exposed for 24 hr to L₂s at either 21°C or 26°C and maintained at their respective exposure temperatures to monitor larval development until larvae molted to the L₃ stage. More than 85% of the exposed copepods showed L₂s in their intestine or hemocoel at 24 hr postexposure. Larvae molted into the L₃ stage in 7 d at 26°C and 12 d at 21°C. Based on these results, species within the Acanthocyclops vernalis–robustus–americanus complex are implied to be natural intermediate hosts of An. crassus in North America.