Background: School based education intervention programs have been effective in increasing awareness to prevent children to start tobacco use when they are most vulnerable. Objective: 1.To find out the magnitude of smoking & smokeless tobacco use among the study population. 2. To assess the knowledge of study population regarding tobacco use. 3. To find out the improvement in knowledge among the experimental & control group after educational intervention; if any. Materials & Methods: Design: Pre-Post quasi experimental study with intervention and control group. Intervention: Baseline pre-intervention data collected from all the participants of both the groups based on pre-tested, semi structured questionnaire. Three sessions of educational intervention at monthly interval were taken for experimental group only. Post - intervention data collected from all the 704 participants and analyzed. Study population: Government school students of classes 7th, 8th & 9th of 12-16 years age group in an urban slum of Kolkata, West Bengal Results: Smokeless form of tobacco is the most prevalent form (67.4%). Post intervention knowledge about tobacco use has increased in experimental study group when compared to control group as P value is statistically significant. Conclusions: The educational intervention program improved knowledge of school children.