Mob justice is a situation where a crowd of people take the law into their own hands and punish an alleged criminal on the spot, often ending with the victim being beaten to death or seriously injured. After we witnessed a mob justice situation in Uganda we wanted to increase our knowledge and understanding of the mob justice phenomenon and examine how it can be prevented. Not much academic literature exists on this topic. We conducted our research in Uganda using two qualitative methods of collecting empirical data; focus group discussions and interviews. The conclusions of our study show that mob justice is a complex phenomenon and the major causes lie on a structural level in the Ugandan society. The judicial system plays an important role as well as structural issues attached to a lower social class. The group psychological mechanisms in a mob group are also connected to structural issues. All of these structural concerns create a tension that, under certain circumstances, results in mob justice. As ways of preventing mob justice the respondents discuss several structural changes as well as sensitization in collaboration with different professional and public actors.