The purposes of this literature review were to: (1) review the sources of mutans streptococci (MS) colonization in children and the effect of MS levels of primary caregivers on children's MS colonization; and (2) evaluate studies examining interventions to reduce transmission of MS from caregivers to their children. Forty-six studies were reviewed. Strong evidence demonstrated that mothers are a primary source of MS colonization of their children. A few investigations showed other potential sources of children's MS colonization, notably fathers. The role of other factors influencing transmission, such as socioeconomic status (SES) and specific cultural or behavioral practices, are unclear. There were at least 12 reports of microbiological interventions to reduce transmission of MS from caregivers to their children. Even though most studies found a reduction of MS in the children and 2 showed significant caries reduction, these studies generally lock consistent findings regarding caries reduction, hove a small sample size and inadequate control groups, and lock blindness of investigators and subjects. The efficacy of microbiological approaches on the caregivers to reduce caries risk in children still needs to be established through more rigorously designed clinical trials.