Theworld has taken unprecedented and stringent preventive and precautionary measures against COVID 19 to control its spread safeguard citizens and ensure their well being. Public adherence to preventive measures is influenced by their knowledge and attitude towards COVID 19.Following the WHO declaration, countries around the globe, including India have been leaning on response plans to respond to the pandemic and contain the virus. Indian government has been vigilantly monitoring the situation and taking specific measures that are in line with the WHO guidelines in dealing with the outbreak. Objectives: To assess the knowledge regarding covid-19 & its preventive measures among adolescents. To find out the association between the level of knowledge regarding covid-19 & its preventive measures with the selected demographic variable. Approach: The research approach adopted for present research is quantitative research aimed assessing the knowledge and preventive measures taken by adolescents during COVID19 in selected school of Dehradun, Uttarakhand.The research design used for this study is descriptive design. This study was one phase collected by self administrating questionnaire method to assess the knowledge and preventive measures taken by adolescents during COVID 19 in selected school of Dehradun, uttarakhand. Result Result related to level of knowledge regarding COVID 19 among adolescents.-11% of samples were having good knowledge, 82% samples were having average knowledge and 7% samples were having poor knowledge. Preventive measures taken among adolescents for COVID 19.- It was found through the conducted study that there is very association between level of knowledge and selected demographic variables.The result findings exhibited that the one variable that is level of education at 0.004 level of significance had statistical significant association with the knowledge score Conclusion: The purpose of the present study was to find out the knowledge and preventive measures taken by adolescents during COVID 19 and to find out the association between knowledge regarding COVID 19 and its preventive measures with the selected demographic variable.