This paper, Responsible Business Conduct for Institutional Investors: Key Considerations for Due Diligence under the OECD Guidelines for Multinational Enterprises, helps institutional investors implement the due diligence recommendations of the OECD Guidelines for Multinational Enterprises in order to prevent or address adverse impacts related to human and labour rights, the environment, and corruption in their investment portfolios. The paper identifies key actions for asset managers and asset owners under each step of the due diligence process and includes discussion of key considerations, such as challenges, existing practices, or regulations specific to the investment sector which may impact due diligence approaches. By carrying out due diligence in line with the OECD Guidelines, investors will not only be able to avoid negative impacts of their investments on society and the environment, but also avoid financial and reputational risks, respond to expectations of their clients and beneficiaries and contribute to global goals on climate and sustainable development. Increasing, failing to consider long-term investment value drivers, which include environmental, social and governance issues, in investment practice is seen to be a failure of fiduciary duty. Since the introduction of the Paris Climate Agreement in 2015, investors have been facing increasing expectations to manage climate risks in their portfolios. International financial institutions have also signalled plans to mobilise USD 400 billion towards achieving the Sustainable Development Goals (SDGs). Strong due diligence processes can help ensure that investments are put towards projects and companies that behave responsibly and ultimately help achieve the objectives of the SDGs.