<bold>Background: </bold>School physiotherapy programs can promote an increase in health literacy promoting healthier postural habits. This study aimed to verify the effectiveness of this program in improving the theoretical-practical ergonomic knowledge about postures in adolescents and to verify the postural habits adopted.<bold>Methods: </bold>The sample comprised 206 students, 109 (52.9%) being boys, aged 12-19 years old. The measurement instruments included a theoretical-practical test and a scale. The intervention program included one session lasting 90 min, using both theoretical and practical approaches.<bold>Results: </bold>The mean values obtained on the theoretical-practical test before and after the 1-month period were 9.14 ± 2.51 and 13.05 ± 1.41, respectively (p ≤ 0.001). One hundred and ninety-nine (96.6%) students sat with the spine wrongly positioned, 197 (95.6%) students used mobile phones with a cervical flexion, and 165 (80.1%) lifted a heavy object from the floor incorrectly.<bold>Conclusions: </bold>This data revealed that a school physiotherapy program improves ergonomic knowledge in adolescents.