The purpose of this study is to investigate the effectiveness of the disability-understanding program by project method on middle school students\' attitudes toward disability students. The experimental design used in this study, was a pretest-posttest control group design. Seventy two first grade students in middle school were tested during this study. They were randomly placed into two separate groups: experimental and control. A t-test was used to analyze the collected data with the SPSS 10.0. The subjects of this study are as follows: Subjects 1: Will the disability-understanding program by project method have a positive effect on changing the attitudes of non-disabled students toward disabled students? Subjects 2: Will the disability-understanding program by project method have a positive effect on changing component of non-disabled students\' attitudes toward disabled students? The major findings of this study are as follows: First, By the disability-understanding program by project method the experimental group showed a positive change in the attitudes of non-disabled students compared to those in the control group. In other words the disability-understanding program by project method has a positive effect on changing non-disabled students\' attitudes toward disabled students. Second, By the disability-understanding program by project method the experimental group showed a positive change in cognitive, affective, behavioral components in attitudes compared to those in the control group. The disability-understanding program by project method has a positive effect on changing component of non-disabled students\' attitude toward disabled students. In conclusion, the self-directed disability-understanding program by project method has a positive effect on changing the attitudes of non-disabled students toward disabled students. key words : disability-understanding program by project method, disability-understanding program, attitudes of non-disabled students