Focusing on four major sets of investment principles – the UN Principles for Responsible Investment...the Equator Principles, the Environmental and Social Principles of the European Investment Bank...and the OECD Declaration on International Investment and Multinational Enterprises – Investing for sustainable development? takes a first step in assessing the content, take-up, implementation and impact of investment principles. The study finds that the main impact of investment principles on sustainable development so far is mitigation of the worst effects of investments rather than a shift in the underlying basis of decision-making. Investors are generally unwilling to compromise high returns for improved sustainable development outcomes.