The aim of this study is to discover the effects of the TUBITAK 4006 science fair project on the students, which is carried out in a secondary school in Turkey. The research has been carried out with mixed method. The first stage of the research was carried out with Program Effects Case Studies. In this context, interviews were conducted with 24 students and two teachers who are selected by purposeful sampling method. In the second stage of the study, experimental design was used. At this stage, the pre-test and post-test scores of 57 students attending the science fair were compared with 60 students who did not participate in the science fair. The data obtained showed that the students who participated in the science fair increased their science course scores. In addition, the science fair has provided with students some academic and social benefits and contributed to their personality development.