Current research shows that the number of science fairs and science fair participants is increasing. However, other than the growth of participant numbers, there is very little research investigating the benefits of these science fairs and assessing whether science fair projects are worth the time, effort, and money spent on them. The purpose of this study was to explore the impact of science fairs on students' understanding of scientific method and attitudes towards science. Seventh grade students were selected from four schools, which spanned a wide socioeconomic range and varied in whether or not students participated in a science fair. Two questionnaires were developed for this study, one to measure the understanding of scientific method and the other to measure attitudes toward science. A pretest posttest control design was used. Four hundred three students (201 females and 202 males) took the pretest, and four hundred fifty-six students (214 females and males) took the posttest. The experimental group was chosen from schools where participation in the science fair was obligatory. The control group was chosen from schools that didn't hold a science fair. Pretests were given at the beginning of the science class and posttests were given after the science fair. T-tests were used for data analyses of the pretest and posttest results. The results were not statistically significant when the scientific method scores and attitude toward science scores were compared between control and experimental groups. Gender was found to be significant. In the pretest, girls exhibited higher scientific method scores than boys. The pretest scientific method scores dropped for both genders in the posttest. However, this drop was similar between genders. In contrast, males who participated in the science fair had higher attitude toward science test scores before the science fair, yet attitude scores were nearly equal for both genders after the science fair. (Author)