The present article aims to review the current knowledge about acquisition, transmission and colonization of Streptococcus mutans (S. mutans), especially in children. S. mutans is the primary species associated with the development of dental caries in children. Various serological strains of this bacteria have been identified. A recently discovered strain, serotype k, of S. mutans is strongly associated with causing systemic disease and endocarditis. Being transmitted primarily from the saliva of the mother, this bacterium colonizes the mouth of an infant as soon as the primary teeth erupt. There is an interplay of various host and bacterial factors that are associated with the colonization of S. mutans in the oral cavity of children. Despite a vast knowledge of microbial ecology and pathogenicity of S. mutans, dental caries continues to be one of the most chronic prevalent oral diseases in the population worldwide. An explorative research about the pathogenic strains of this bacterium could help in preventing dental caries right at the stages of infancy thus providing a control on its outbreak.