We seem to have become partisan animals, with Republican or Democratic identification now tied to all of our other social identities and political attitudes. In the height of the campaign season, Americans start to define ourselves based on our partisan side, changing our views to reinforce our identity. Emily West finds that partisan identity is heightened as Election Day approaches and can be made more or less salient in experiments. When partisan identity is brought to the top of the mind, Republicans become more racially resentful--matching their party norm. But induced partisan identity does not explain affective polarization. We don’t seem to hate each other because partisanship is part of our identity. So ideological considerations and other factors still matter for producing and sustaining opposition to the other party and our own partisan identity. It all tends to be self-reinforcing, but there are times and interactions that can dampen the cycle.