FRIENDS for Life is an anxiety prevention programme that integrates cognitive behavioural approach with social and emotional learning. The current study examines the effects of the FRIENDS for Life programme in a school environment, with outcomes focusing on anxiety and aggression. The theoretical basis for the joint prevention and intervention of anxiety and aggression is based on their frequent simultaneous occurrence. Four classes of 4th-grade students (N = 85) were randomly assigned two to intervention and two to a no-treatment control group in a randomized control study. We measured the total anxiety and components of anxiety and the total of aggression and components of aggression with AN-UD and AG-UD aggression scale at pre-, post-, half-year, one-year and one-year-and a half follow-up. The results were inconclusive with regard to the effectiveness of the programme. However, there is some indication of possible effects on the reduction of anxiety and aggression in the boys' sub-sample. This was also the sub-sample that showed higher levels of anxiety and aggression at baseline, suggesting possible difference in the effectiveness of the programme. Proposals are made to replicate the study in a larger format.