My research will examine if within-individual change in emotion can explain when and why individuals engage in prosocial action. That is, can dynamic change in emotion – such as anger – explain the ‘tipping point’ at which someone decides to take action. Almost all relevant previous research has examined variation between individuals, for example, those higher in anger are more likely to act. This research will be novel in that it will test whether change in emotions from one time point to another predicts change in prosocial behaviour; can people’s engagement in prosocial action be predicted by the process of becoming angry, rather than just being angry at a particular point in time?