During the last decade, discussion on shareholder activism concentrated on hedge funds, some seeing them as agents for passive institutional shareholders, bridging the separation of ownership and control, others believing their short-term value-maximization interests differing fundamentally from those of other shareholders. Some have seen hopes for long-term activism in institutional shareholders such as pension funds. In the European Union, activism is seen positively, encouraging proposals to enhance shareholders’ rights against the boards’ discretion. The purpose of this chapter is to focus on institutional investor activism and its impact on both their ultimate beneficiaries and their target companies, and how investors could be incentivised to more sustainable behaviour in their activism. Albeit the focus is on the European Union, institutional investors are global. A broader perspective including North America and Asia is therefore taken. The most important impact of institutional activism is arguably normative, causing changes in corporate governance. Specific attention is therefore given to governance questions.