Contextual differences in the association between different forms of aggressive behavior and victimization were studied with a sample of 197 boys and 149 girls from mixed-sex schools and in 336 girls from all-girl schools (M = 10.21 years of age) in two cities in Colombia. Results showed that boys generally engage in more physical than relational aggression, whereas girls engage in more relational than physical aggression. Among boys, the association between aggression and victimization was significant only for the measure of relational aggression, whereas, for girls, victimization was significantly correlated only with physical aggression. This latter association was found to be significantly stronger for girls from the all-girl schools than for the girls from the mixed-sex schools. These findings are discussed in terms of how mixed-sex and same-sex groups, as different forms of peer context, affect the social dynamics related to the association between aggression and victimization.