Background: This study examined the combined influence of gender variables (specifically gender stereotypes, sexism, and genderism/transphobia) as well as racism/xenophobia and attitudes toward bullying roles on gender-bashing. Methods: A trans-cultural sample of 2410 Spanish and Portuguese students participated in the study (mean age = 15.13). Structural equation modeling and multiple group analyses were used to examine the relationships among variables. Results: The model revealed a good fit with the data for the whole sample. Results showed that instrumentality, hostile sexism, genderism/transphobia, racism/xenophobia, and positive attitudes toward the bully were positively correlated with gender-bashing. An inverse pattern was also observed: expressiveness, benevolent sexism, and positive attitudes toward the defender were negatively correlated with gender-bashing. Overall, the eight variables explained 48% of the variance of gender-bashing. Structural relationships among the assessed constructs were equivalent for girls and boys, and for Spain and Portugal. Conclusions: These results reveal the need to implement inclusive educational policies to improve school health, which promote expressiveness, egalitarian attitudes, and sexual and cultural diversity.