Recent research has consistently highlighted the importance of vaginal ecology in acquisition of sexually transmitted infections (STIs). Our understanding of vaginal microbiota, while still quite limited, has grown rapidly in the past decade. This symposium includes discussions of the most recent empirical findings on the factors responsible for the disruption of healthy vaginal microbiota; current approaches to restoring a healthy vaginal environment and the challenges that still remain; the effects of sexual intercourse on vaginal ecology; and the impact of vaginal microbiota on acquisition of STIs upon exposure.