Relational aggression is common among girls. It can be distressing for the victim and may not always be recognised as a form of bullying. This paper evaluates a school–based intervention designed to help girls understand relational bullying. Girls from a single‐sex school completed a two‐stage evaluation of the intervention. Students showed greater awareness of relational bullying after the intervention and indicated that it would influence them to change their behaviour. At follow‐up, retention of knowledge was good. Students reported greater self‐monitoring of behaviour and less exclusivity. While this is encouraging, we cannot conclude that all negative behaviours ceased. Implications and limitations of this study are discussed. Copyright © 2010 John Wiley & Sons, Ltd.