Schools have prioritized fighting cyberbullying by implementing intervention programs. Yet few interventions have been studied for their effectiveness in reducing cyberbullying and improving socio-emotional aspects in the classroom. This study reports the results of the Safe Surfing intervention program designed to reduce cyberbullying in WhatsApp classmate discourse. Data were collected in the 2017-2018 school year from 533 students in 25 fourth- to sixth-grade classes (50% females) in six elementary schools in Israel. Two of the schools served as the control group. Results indicated a significant decrease in WhatsApp cyberbullying victimization and a significant improvement of classroom climate and student sense of class belonging in the experiment group. This compared with a significant increase in cyberbullying and a significant decrease in classroom climate and student sense of belonging in the control group. Educational implications are discussed. The findings demonstrate the achievements of the anti-cyberbullying intervention program, alongside the threats of avoiding intervention.