Abstract: Substance abuse among adolescents poses significant risks to their health and wellbeing. Purpose: Evaluate the effectiveness of a cognitive behavioral therapy on mental resilience and decision-making style among secondary school students prone to substance abuse. Design: A Quasi experimental research design was utilized. Setting: This study was conducted at four secondary schools at Menoufia Governorat, Egypt. Sample: A purposive sample of 117 secondary students who fit the inclusion and exclusion criteria. Data collection tools: Four tools were used: 1) A structural interview questionnaire to assess socio-demographic characteristics, 2) The child and youth resilience measure (CYRM-17), 3) Decision making style Scale, 4) Drug abuse screening test (DAST-20) adolescent version Results: There was three quarters (75.2%) of the studied students had substantial level of drug abuse, and only 23.1% had sever level of drug abuse. There was a significant improvement in resilience subscales and total among the studied students after the cognitive behavioral therapy than before at P value <0.001. There was a highly statistically significant improvement in rational, dependent, spontaneous decision-making styles. While there was non-significant improvement in intuitive and avoidant styles among the studied students after the cognitive behavioral therapy. Also, there was a highly statistically significant improvement in total decision-making style. There was a highly statistically significant positive correlation between total resilience and total decision making. Conclusion: Cognitive behavioral therapy has a positive effect on improving total resilience and total decision making. Recommendation: Incorporate cognitive behavioral therapy as a treatment modality for students prone to substance abuse