Introduction: The literature review indicated that oral health is a serious health issue among Indian school adolescents. In India, less than 5% of adolescents have access to organised public dental health services in order to identify and treat dental caries at an early stage. Oral health literacy is important for adolescents to prevent and manage dental caries in their permanent teeth. Currently, there is no formal oral health education available in both the primary and secondary level school curriculum in Tamil Nadu. Objective: This thesis was conducted to collect baseline data to measure the epidemiology of dental caries and the level of oral health literacy among adolescents in rural and urban schools of Tamil Nadu, India. Methods: Oral health literacy and the epidemiology of dental caries were measured in 974 adolescent school students (12-15 year-olds) from both rural and urban areas of Tamil Nadu, India. There were three research questions answered in this thesis using a cross-sectional descriptive correlational quantitative study design. The first research question was addressed by measuring the Decayed, Missing and Filled teeth index (DMFT) using the WHO oral health survey method. The second research question was addressed by measuring the oral health literacy of 974 adolescent participants using a self-administered questionnaire developed for this study. The third research question was addressed by examining the association between the severity of dental caries (question 1) and oral health literacy (question 2). Results: The oral health survey indicated that prevalence of dental caries among adolescents in rural and urban parts of Tamil Nadu was 61.4% with an average DMFT score of 2.03. Multiple regression analyses indicated factors such as gender, age, mother’s education, type of schools and community/caste as significant predictors of dental caries. This is the first study to assess the impact of community on oral health literacy and status of adolescents. Almost 92% of participants reported that they had never been to a dentist. In total, 1980 teeth were affected and 98.6% (1953) affected teeth were decayed and not filled. The Cronbach’s alpha score (0.651) demonstrated the developed questionnaire had good internal consistency. In total, 35% of participants had poor oral health literacy (OHL) skills and only 8.3% of participants had good OHL skills to prevent dental caries. Parent’s education, gender and community/caste were identified as significant predictors of OHL in the regression analysis. A strong negative association between oral health literacy scores and dental caries prevalence and severity was identified in the study. Conclusion: The current study is the first to find an association between oral health literacy and dental caries in an adolescent population both in international and Indian literature. The prevalence of dental caries was decreased and severity of dental caries was increased when compared to previous research in Tamil Nadu. This result implies an imbalance in availability of oral health services in Tamil Nadu, India. The study results also imply that the majority of the study population had poor or moderate oral health literacy to prevent and manage dental caries. Females, Scheduled Caste and Tribes attending public schools in rural areas were identified as the more vulnerable populations to get affected by dental caries due to their poor oral health literacy. Oral health policies should be targeted to these adolescent populations in the Tamil Nadu region. Improving oral health literacy education in the school and pre-school curriculum could help to manage oral health in adolescents.