Victims of bullying are at increased risk of developing psychosocial problems. It is often claimed that it helps victims when others stand up against the bullying and when defending is typical (descriptive norm) or rewarded with popularity (popularity norm) in classrooms. However, recent work on the healthy context paradox suggests that victims – paradoxically – tend to do worse in more positive classrooms. Therefore, it is possible that defending norms are counterproductive and exacerbate victims’ adjustment difficulties, possibly because social maladjustment is more apparent in classrooms where everybody else is doing well. The current study examined whether descriptive and popularity norms for defending predicted victims’ classroom climate perceptions and psychosocial adjustment. Using data of 1,206 secondary school students from 45 classrooms (Mage = 13.61), multi-level analyses indicated that descriptive norms for defending increased rather than decreased negative classroom climate perceptions and maladjustment of victimized youths. In contrast, popularity norms for defending positively predicted all students’ classroom climate perceptions and feelings of belonging, except victims’ self-esteem. Interventions may benefit more from promoting popularity norms for defending rather than descriptive norms for defending in secondary schools. All information about the content of the files is described in 'read me_Laninga-Wijnen et al_2021.pdf'. This file also contains information about the recruitment, participants and data collection. Data and the syntax for the analyses as presented in the paper are also stored.