We assessed the implementation characteristics and children's appraisal of FRIENDS for Life, a school-based prevention program targeting childhood anxiety and depression, and its relation to program outcomes. Prevention workers delivered the program using specific therapeutic skills, but did not adhere completely to the protocol. However, this appeared not to negatively affect program outcomes. We found few other significant associations between program integrity and outcomes. Children's participation was good and they appraised the program positively. Children rated the program more positively when protocol adherence was lower. In conclusion, a highly protocolled intervention can be successfully transferred to daily school practice.