Civility relates to following rules that typically are aimed at promoting positive social behaviour. A lack of civility can be either intentional (e.g., insulting a classmate) or unintentional (e.g., packing up early). Civility is an important issue within classroom settings because it not only influences classroom functioning, but may also serve as a gateway to more serious antisocial behaviour. With regard to the latter, we were specifically interested in whether attitudes towards behaviour deemed as ‘incivility’ were associated with more serious bullying behaviour. Beyond any associations with each other, we were also interested in whether incivil attitudes and bullying share common personality correlates among adolescents. To answer these questions, our study examined the links between HEXACO personality traits, intentional and unintentional incivility, and bullying. Adolescents (n = 396) completed self-report questionnaires, and results were analysed with structural equation modelling. There were similarities and differences between the personality correlates of bullying and attitudes towards the two kinds of incivility. In particular, we found a significant association between personality and bullying behaviour that was mediated by attitudes towards intentional incivility. Our results highlight the importance of increasing awareness of educators regarding classroom incivility, given its potential negative implications within a school setting.