Identification of strain-specific markers on Neisseria gonorrhoeae that are capable of differentiating gonococci into a large number of distinct classes could facilitate analysis of patterns of gonorrhea transmission and application of gonorrhea control measures. A panel of 12 monoclonal antibodies to gonococcal outer membrane protein IA (PrIA) and IB (PrIB) was used to classify 1,433 strains serologically in a worldwide survey. Eighteen PrIA and 28 PrIB serovars were identified, and a nomenclature is proposed. Gonococcal strains were classified further by auxotyping. Auxotyping and serotyping served to classify the 1,433 isolates into 107 unique auxotype/serovar classes. Dual classification by auxotype and serovar can be used to identify epidemiologically related gonococcal infections in order to test the effectiveness of innovative, focused measures to control gonorrhea.