Scholars investigating the role of self-interest in determining policy preferences find that self-interest has weak effects. However, researchers have refined their concepts of self-interest and are now finding a greater role for it (e.g., Crano 1995). We continue along this line of research, considering different mechanisms by which self-interest may come to be important. We argue that measuring people’s perceived self-interest in a policy (which we call vested interest) is important for understanding how people pursue their self-interest. We find that while life circumstances can cause people to endorse vested interest, emotion is an important mediator of this relationship. Finally, we test the notion that value change mediates between vested interest and support for a policy, and find evidence for a reciprocal relationship.