We argue that the growth rate, but not the level of aggregate income, affects the support for extreme political parties. In our model, extreme parties offer short-run benefits to part of the population at the expense of a minority. Growth effects on the support for such parties arise when uncertainty exists over whether the same subset of individuals will receive the same benefits in the future. More people are willing to take political risks if economic growth is slow. Based on a panel of 16 European countries, our empirical analysis shows that slower growth rates are associated with a significant increase in right-wing extremism. We find no significant effect of economic growth on the support for extreme left-wing parties.