Purpose: This study aims to analyze and compare selected physical fitness, physiological, and psychological variables among boys from government, government- aided, and private schools in the Chennai district. The purpose is to understand how different school environments impact these variables and to provide insights that can inform policy and practice in physical education and health promotion. Methodology: A sample of 300 boys aged 12-15 years was selected through stratified random sampling, with 100 boys from each school type (government, government-aided, and private schools). Physical fitness was measured using the Fitness Gram test battery, physiological variables such as BMI, resting heart rate, and blood pressure were assessed using standard clinical procedures, and psychological variables were evaluated using the Rosenberg Self- Esteem Scale and the Perceived Stress Scale. Data were analyzed using ANOVA to compare the means across the three school types, with post-hoc tests conducted to identify specific group differences. Conclusion: The study found significant differences in physical fitness, physiological health, and psychological well-being among boys from different types of schools. Boys from private schools exhibited better physical fitness and lower stress levels compared to their peers in government and government-aided schools. These findings highlight the influence of socio-economic factors and access to resources on students' health and suggest the need for targeted interventions in government and government- aided schools to improve physical and psychological well- being among students.