My PhD and post-doctoral work centered upon identifying genes required for bacterial cell division and sporulation (1985-1993). During my 28 years at the US Centers for Disease Control and Prevention, I have focused primarily on surveillance of circulating strains of the 3 major streptococcal pathogens, S. pneumoniae, S. pyogenes, and S. agalactiae. Up until about 12 years ago I naively believed that PCR-based detection of sequences specific for pneumococcal capsular serotypes in upper respiratory specimens would also be specific for the pneumococcal species itself. I soon realized that in different pneumococcal carriage surveys that “pneumococcal serotype-specific” PCR amplicons were more commonly indicative of non-pneumococcal species such as Streptococcus mitis, Streptococcus oralis, and Streptococcus infantis that expressed these same serotypes. It is possible that the broad species diversity of capsular serotype expression in the human upper respiratory tract has profoundly affected the global landscape of pneumococcal disease and population immunity. It follows also that analyses of more representatives of pneumococcal cps operons within related streptococcal species might answer questions of the species origins of different serotypes and frequencies of interspecies cps transfer events. The elucidation of the capsular serotype overlap between the Mitis group species is at a very early stage. Here I will summarize some of our findings.