Can personality traits predict willingness to fight or even die for one's heritage culture group? This study examined insecure attachment dimensions – avoidance and anxiety – as predictors of perceived rejection from heritage culture members and, in turn, greater endorsement of extreme pro-group actions. Expressing extreme commitment for the heritage culture may represent an attempt by insecure individuals to reduce their perceived marginalisation and reaffirm their heritage culture membership and identity. Participants completed measures of attachment dimensions, intragroup marginalisation, and endorsement of extreme pro-group actions. Individuals who were high in anxiety or avoidance reported heightened intragroup marginalisation from family and friends. In turn, friend intragroup marginalisation was associated with increased endorsement of pro-group actions. Our findings provide insight as to why insecurely attached bicultural individuals may be drawn to endorse extreme pro-group actions.