Introduction: Although bullying is a phenomenon which directly affects teachers, they receive little preparation in how to handle it. One way to correct this situation is to include specific content about bullying within their initial university curriculum. We present a study that shows how a specific course on bullying affects trainee teachers' knowledge, perceptions and attitudes towards this problem. Method: The participants (n = 199) are trainee teachers (university students) of Pre-School, Elementary and Secondary Education, distributed between an experimental and a control group. The "School Bullying Questionnaire" (Nicolaides, Toda & Smith, 2002) was adapted to Spanish for this research, and used for data collection. A quasi-experimental pre-post design with non-equivalent groups is used. Results: The results indicate statistically significant improvement among members of the experimental group in terms of characterizing the phenomenon, detecting the agents involved, characterizing victims and aggressors, choosing strategies to deal with bullying, as well as improvement in perceived self-efficacy for confronting the problem effectively. Discussion and conclusions: Results allow us to affirm that members of the experimental group have modified and improved their knowledge and perceptions about bullying, as has been seen in other studies. Specific training has a positive impact and makes clear the need to include specific content about school-related problems in the pre-service teachers' curriculum. (Contains 1 graph, 7 tables, and 1 footnote.)