General strain theory (GST) is the most comprehensive version of strain theory and can explain both instrumental and expressive violence. In GST, strains pressure people to take corrective action by generating negative emotions, especially anger. This chapter provides an overview of the core arguments and research on GST, violence, and aggression and describes recent extensions of the theory. Special attention is given to one type of strain that has received much recent attention: unjust treatment by criminal justice officials.