The current study aimed to identify the level of cognitive distortions and aggressive behavior among the upper basic stage students in Hebron city, it also aimed to investigate the relationship between cognitive distortions and aggressive behavior, and to investigate the difference in both variables according to gender and academic level. A stratified random sample of (381) students was used to achieve the objective of the study. Two scales were developed: the aggressive behavior scale consisting of (29) items, and the cognitive distortions scale consisting of (23) items; the psychometric characteristics of the scales were verified. The study found that the levels of cognitive distortions and aggressive behavior among the students were moderate. Also, a positive correlation between cognitive distortions and aggressive behavior was found. Moreover, the study revealed statistically significant differences between the means of cognitive distortions and aggressive behavior due to gender in favor of males, in addition to statistically significant differences in the cognitive distortions level due to the academic level in favor of eighth grade students. The study concluded with recommendations to provide students with programs aimed at building positive behaviors.