According to Minsky's financial instability hypothesis, financial crises are caused by increasing debt burdens. The purpose of this paper is to argue instead that financial crises are caused by class and intra-class conflict. The 1966 financial crisis is particularly significant, from the perspective of Minsky's financial instability hypothesis, because it divides the postwar Golden Age of US capitalism from the current period of recurrent financial crises. After showing that increasing debt burdens do not account for the 1966 financial crisis, this paper explains the 1966 financial crisis in terms of class and intra-class conflict.