This paper focuses on the fees that are charged to participants in mandatory, defined contribution pension systems, focusing on the experience of Latin America, Central and Eastern Europe, Australia, and Sweden. In order to compare fees across countries, this paper looks at the evolution of a simple cost measure, the ratio of annual fees to assets under management. The relatively high fee to assets ratios in some Latin American and Central and Eastern European countries can be partly explained by the recent implementation of their private systems. However, system maturity cannot explain all differences observed between countries. The paper argues that the particularly low fees observed in Bolivia and Sweden at the inception of their respective systems stem largely from a decision to force cost competition among providers via a central agency or =clearing house‘.