We determined a polymerase chain reaction (PCR)–based method to identify the sex of greater roadrunners (Geococcyx californianus). We found that previously reported primer combinations used in other bird species did not work reliably in roadrunners. However, a novel primer combination (P2-1237L) allowed for consistent and reliable sex identification of roadrunners. Conducting several PCR replicates per sample helped to identify occasional preferential amplification of the Z band that could occur in females (the heterogametic sex; i.e., WZ). Identifying the sex of individuals will allow for examination of sex-associated differences in home range size and habitat use, population demographics, and parenting behavior, as well as for a better understanding of the social system of roadrunners.