The current decline in the performance of secondary school students in Physics in the Senior School Certificate Examination (SSCE) has become a major concern for the stakeholders in the field of education. This may perhaps, be partly due to the strict adherence of Physics teachers to the use of conventional teaching method in teaching Physics. This study was therefore carried out with the aim of evaluating the comparative effectiveness of Self-instructional Print Media and the conventional teaching method on secondary school students' achievement in Physics in Osun State.