This study adopts a creative methodology to investigate how cartoons can serve as visual representations of primary school children's understanding of bullying and compares how their understanding develops over time. The study was carried out in Northern Ireland where the "Addressing Bullying in Schools (Northern Ireland) Act 2016" will require schools to follow a new statutory definition of bullying. To investigate the behaviours that children associate with bullying, a set of 16 original stick figure cartoons was devised. The cartoons were shown to a sample of Year 3 and Year 7 pupils from two different primary schools in Northern Ireland (N = 90). Pupils were asked to record which scenarios they considered to be bullying or not bullying. They were then invited to write their own definitions of bullying and to creatively illustrate them using stick figures. A total of eight gender-specific pupil focus groups were conducted across the two schools to explore the key elements which the pupils considered significant to their understanding of bullying. The study highlights the value of this creative participatory approach and found a wide range of behaviours which children associate with bullying but also considerable variation among pupils in terms of their understanding. Levels of understanding in Year 7 were more nuanced than those in Year 3, but there were no discernible differences by pupil gender. Conclusions are drawn in terms of the new legislation in Northern Ireland, but also in relation to the benefits of adopting a creative research methodology using cartoons as visual representations with children to explore complex pastoral issues.