The OECD Principles of Corporate Governance embrace the underlying assumption that shareholders can best look after their own interests, provided they have sufficient rights and access to information. The increased presence of large institutional investors in the last decade fostered the expectation that a new breed of highly skilled and well resourced professional shareholders would make informed use of their rights, promoting good corporate governance in companies in which they invest. Those prospects are reflected in Principles II.F and II.G, added in 2004 to cover disclosure of voting policies, managing conflicts of interest and co-operation between investors. However, institutional investors are not like other shareholders but have a unique set of costs, benefits and objectives. Accordingly, they have not always behaved as desired. This report investigates their behaviour by way of three peer reviews on the implementation of Principles II.F and II.G (Australia, Chile and Germany) and a general review of academic research and country experience.