Mediation analysis has been confirmed as a very useful statistical tool in the social sciences, especially in school-related studies. This type of analysis was used in the present study to examine the mediating role of classroom climate (measured with the classroom environmental scale), categorized into three dimensions, namely involvement, affiliation, and teacher support, on the relationship between peer victimization and peer aggression. The participants consisted of 2011 adolescents (50.67% boys and 49.32% girls), aged between 12 and 18 years old (M = 14.17; SD = 1.47), enrolled in schools in Andalusia (Spain). Findings revealed a significant direct relationship of all the dimensions. They also revealed that teacher support was the only dimension that mediates in the relationship between peer violence and peer aggression. The results and their implications for improving classroom climate and school violence are discussed.