According to parents and teachers, 16.4% [15.4; 17.4] of elementary school children were likely victims of bullying (victimization), 17.9% [16.8; 19.1] exhibited aggression, and 6.1% [5.5; 6.8] experienced both victimization and aggression; Children who were likely victims of bullying and those exhibiting aggressive behavior were more frequently found to have at least one probable mental health disorder in the emotional, oppositional, or inattention/hyperactivity domains; among those who exhibited both victimization and aggression, 40.9% [36.1; 45.8] had at least one of these disorders; Vulnerability factors for victimization and aggressive behavior were identified among individual characteristics (learning disabilities, special educational needs, prematurity, body size, and prosocial skills) and family characteristics (educational attainment, perception of household finances, parental depression or anxiety, and perceived social support); the differences observed based on school environment characteristics (school district; level of social disadvantage in the municipality) can be explained by these individual and family factors.