Dr Heyzer was the first woman to serve as Executive Secretary of the UN ESCAP since its founding in 1947, and the first Executive Director outside of North America to lead the UN Development Fund for Women (1994–2007). She played a key role in the Security Council’s adoption and Implementation of Resolution 1325 (2000) on Women, Peace and Security, undertaking many missions to conflict-affected areas worldwide. Dr Heyzer served under four UN Secretary-Generals, notably as Special Adviser for Timor-Leste (2013–2015), a member of the UNSG’s High-Level Advisory Board on Mediation (2017-2021) and as the UNSG’s Special Envoy to Myanmar (2021–2023). She has served on numerous international boards and advisory committees, including UNDP’s Human Development Report, the Asian Development Bank’s Eminent Persons Group, the Board of Trustees of the National University of Singapore and a member of the Governing Board of the Lee Kuan Yew School of Public Policy (NUS), and the Kofi Annan Global Commission on Elections and Democracy in the Digital Age. She was also on the High-Level Commonwealth Commission on Respect and Understanding, and a jury member of the US Secretary of State Hillary Clinton’s Innovation Award for Women’s and Girl’s Empowerment (2010).