Adolescence is a critical period of human development manifested at biological, psychological and social level of integration. Approximately 18-20% of the Indian population constitutes adolescents in the age group of 10-19 years. More than one half of all mental disorders and problems occur due to substance abuse among adolescents. The effective and appropriate preventive intervention can only enhance the knowledge regarding the consequence of substance use and develop attitude towards prevention of use of gate way substances. The study attempts to determine the effectiveness of school based teaching programme on knowledge and attitude regarding prevention of substance abuse among adolescents in selected schools of Mangalore. A quasi-experimental control group design was adopted for the study. Among 100 adolescents, 50 each were assigned to experimental and control group. Data collection was done by using validated structured knowledge questionnaire and Likert attitude scale. The ‘t’ value (t=22.29) was computed between mean pre-test and post-test knowledge scores among experimental group and control group. Also ‘t’ value (t=21.27) was computed between mean pre-test and post-test attitude scores among experimental group and control group .The results revealed that there was a significant increase in knowledge and attitude score among experimental group (t98=1.66, p<0.05). This shows that the school based teaching programme was effective in gaining knowledge and favourable attitude towards prevention of substance abuse among adolescents. There was also significant association between knowledge scores of adolescents and selected baseline variables like types of family (χ²=5.464, p><0.05) and educational status of father (χ²=5.653, p><0.05).
