Lactobacilli have been considered as major contributors to human dental caries for over a century. Recentin vitromodel studies have shown that when compared toStreptococcus mutans,a keystone pathogen of human dental caries, the ability of lactobacilli to form biofilms is poor, although differences exist between the different major species. Further studies using molecular and bioinformatics approaches provide evidence that multiple mechanisms, including adhesin-receptor mediated physical contact withS. mutans, facilitate the adherence and establishment of lactobacilli on the tooth surface. There is also evidence that under conditions like continuous sugar consumption, weak acids and other antimicrobials such as bacteriocins from lactobacilli can become detrimental to the microbial community, especially those in the proximity. Details on the underlying mechanisms of how differentLactobacillussp. establish and persist in the highly complex microbiota on the tooth surface await further investigation.