This study investigates the vaginal microbiome of 396 asymptomatic North American women from four ethnic groups (white, black, Hispanic, and Asian) to understand how it prevents urogenital diseases and maintains health. The vaginal bacterial communities were characterized using pyrosequencing of barcoded 16S rRNA genes, revealing five major groups, four dominated by *Lactobacillus* species and one with higher proportions of anaerobic organisms. The proportions of these groups varied significantly among ethnic groups, with Hispanic and black women having higher vaginal pH and lower Nugent scores, indicating a higher prevalence of non-*Lactobacillus*-dominated communities. The study also identified core microbial taxa associated with Nugent scores and found that the vaginal microbiome is not a single, universal "core" but rather consists of multiple core microbiomes defined by community groups. These findings highlight the importance of considering individual differences in vaginal microbiota composition for personalized medicine and disease risk assessment.This study investigates the vaginal microbiome of 396 asymptomatic North American women from four ethnic groups (white, black, Hispanic, and Asian) to understand how it prevents urogenital diseases and maintains health. The vaginal bacterial communities were characterized using pyrosequencing of barcoded 16S rRNA genes, revealing five major groups, four dominated by *Lactobacillus* species and one with higher proportions of anaerobic organisms. The proportions of these groups varied significantly among ethnic groups, with Hispanic and black women having higher vaginal pH and lower Nugent scores, indicating a higher prevalence of non-*Lactobacillus*-dominated communities. The study also identified core microbial taxa associated with Nugent scores and found that the vaginal microbiome is not a single, universal "core" but rather consists of multiple core microbiomes defined by community groups. These findings highlight the importance of considering individual differences in vaginal microbiota composition for personalized medicine and disease risk assessment.