The purpose of this study was to examine how school personnel describe and interpret the phenomenon bullying among girls, and also what their interpretations are based upon. More specifically its aim was to find out what characterizes and causes girl-to-girl bullying, according to school welfare officers and teachers. We wanted to find out how school personnel look upon aggression among girls and social expectations on girls behavior. The analysis was based on two kinds of perspectives: one focusing on gender and one focusing on power in relationships. Research shows that girl-to-girl bullying is hard to observe and that this problem has been invisible in earlier studies. We thought that this phenomenon needs to be brought up and that is one of the reasons why we wanted to examine this subject. This study was based on qualitative interviews with school welfare officers and teachers. A main theme in our study is that our respondents describe girl-to-girl bullying as subtle and quiet. We also found that some of our respondents disagreed on this statement. Their opinions were mainly based on their own experience from working in a school environment. As a conclusion we found out that factors such as social maturity and gender roles can be used as explanations on the phenomenon girl-to-girl bullying. We found out that our tools, power and gender theories, could not fully explain why girls bully in a certain way and how school personnel interpret the phenomenon. More knowledge is needed to understand more about girl-to-girl bullying.