This paper examines the rationale, nature and financial consequences of two alternative approaches to portfolio regulations for life insurers and pension funds, namely prudent person rules and quantitative portfolio restrictions. The argument draws on the financial-economics of investment and the differing characteristics of institutions' liabilities, as well as evidence drawn from major OECD countries. The overall conclusion is that prudent person rules are superior to restrictions, particularly for pension funds, except in certain circumstances that may hold temporarily in emerging market economies.