This article surveys the relevant literature and provides a theoretical perspective on the relationship between the various models of public regulation in Western economies. Anglo-American regulatory regimes are guided by a basic principle: inherited from trust law, fiduciary duty is the golden rule (model 1) even if its elabouration typically runs to many thousands of pages in statute. Pension-fund trustees have significant discretion in choosing the means by which they set about enhancing and protecting the welfare of others. In many respects, regulatory frameworks (model 2) that cover private pension funds provide a mandate and a set of constraints; such regulatory regimes are often silent on the issue of how best to fulfil the mandate. The article argues that both models of regulation are insufficient – the market (model 3) has a vital role to play in ‘regulating’ pension funds. Various regimes of regulation exist, combining in different ways the three models noted above. In the penultimate section of the article, the implications of these different regimes are considered with reference to the need to balance the interests of plan participants (beneficiaries and retirees) with current employees and plan sponsors. Finally, implications are drawn for the design of regulatory regimes.