Background & objectives: Students bullying, especially in the adolescence period, is a prevalent problem in the schools, that emotional dysregulation is posed as a one cause of it. Considering this issue, the aim of this study was to investigate the relationships between emotion regulation and emotion expression styles with bullying behaviors in adolescent students.

  Methods: The method of this study was correlation. Whole male students of secondary and high schools in Ardabil at 90-91 educational year comprised statistical population of this research. Two hundred thirty students, were selected by multistage cluster sampling method, responded to the questionnaires of bullying/victimization, emotion regulation and emotion expression. Gathered data were analyzed by Pearson correlation and multiple regression tests.

  Results: The results showed that victimization by bullying has positive relationship with cognitive reappraisal (r= 0.15, p<0.02), emotion suppression (r= 0.47, p<0.001), and positive expression (r= 0.25, p<0.02), but has negative relationship with impulse severity (r= -0.35, p<0.001), and negative emotion expression (r= -0.43, p<0.001). Furthermore bullying has a positive relationship with cognitive reappraisal (r= 0.14, p<0.03), impulse severity (r= 0.31, p<0.003), and negative expression (r= 0.29, p<0.001), but has negative relationship with emotion suppression (r= 0.28, p<0.001), and positive expression (r= 0.24, p<0.001). In sum emotion regulation and emotion expression styles explained 36 percent of the variance of the victimization by bullying and 19 percent of the variance of the bullying. 

  Conclusion: This research demonstrated that emotion dysregulation at the adolescent period plays important role in bullying and victimization, thus the training of emotion regulation abilities is suggested as the one of interventions methods for this behavioral problems.