Background: Oral health is one of the most common chronic diseases among school children in Sri Lanka. However, there is little or no priority given for oral health preventive strategies. The role of mother or the primary carer of children was identified as significant in oral health promotion. In this context it was vital to empower mothers or care givers of preschool children to improve oral health of children. Objectives: To develop and implement an intervention to promote the oral health of preschool children. To assesses the oral health knowledge and selected oral health care practices of mothers or care givers of preschool children before and after the intervention. Methods: A community based quasi experimental study was conducted in the District of Colombo, Sri Lanka. An intervention in the form of a lecture discussion based on a booklet developed for this study was implemented. An interviewer administered questionnaire was used to assess oral health knowledge and practices before intervention and six months after the intervention. Results: At pre intervention, both intervention and control groups were similar except for Oral health practices and house hold food practices. Oral health knowledge, Oral health practices, tooth brushing practices of preschool child and Household food practices were significantly higher in intervention group at post intervention(p <0.005). Conclusion: Mothers/care givers of preschool children were able to improve and maintain positive practical oral health care behaviours after an educational intervention. However, changes in food practices could not be achieved at the same level of significance