John Alderdice trained in medicine, psychiatry and psychoanalysis, applying his skills in teaching, research, and clinical work in the Faculty of Medicine at Queen’s University Belfast, and at the National Health Service Centre for Psychotherapy that he established in Belfast, but he also took these understandings into politics to address the long-standing political violence in Northern Ireland.

From 1987 to 1998, he was the Leader of Northern Ireland’s Alliance Party and one of the negotiators of the 1998 Belfast/Good Friday Agreement that ended the centuries-long violent political conflict in Ireland. He then became the first Speaker of the new Northern Ireland Assembly, serving until 2004 when he was appointed one of the four members of the Independent Monitoring Commission, charged by the British and Irish Governments with overseeing security normalization in Ireland. The IMC completed its work in 2011, but in 2015 – after the ‘Fresh Start Agreement’ – he was appointed by the First and Deputy First Ministers of Northern Ireland to a three-person panel charged with reporting on a strategy for disbanding paramilitary groups in Northern Ireland. This report was completed and published in June 2016.

Since 1996 Lord Alderdice has been an active Liberal Democrat member of the House of Lords, the upper chamber of the British Parliament, and was Convenor/Chair of the Liberal Democrats in the House of Lords from 2010 to 2014 during the Conservative/Liberal Coalition. In 2020-2021 he was a Deputy to the Lord Speaker, and also a member of the COVID-19 Select Committee of the House. He is currently a member of the House of Lords Select Committee on International Relations and Defence and in 2025 he was appointed the UK Trade Envoy to Azerbaijan and five countries in Central Asia.

Always a committed liberal internationalist, he was from 2005 to 2009 the President of Liberal International, the global family of some 100 liberal political parties.  In 2015 he was awarded the Liberal International Prize for Freedom – the only former President of LI to have received this prestigious award – and in the same year he was elected Presidente d’Honneur of Liberal International – a life-time honorific position reserved for some former Presidents. In 2025 he was elected President of the National Liberal Club in London.

Having retired from clinical psychiatry some years ago he has continued to work on conflict issues with various academic positions at the University of Oxford where he is now an Honorary Fellow at Pembroke College, and a Professor of Practice both at the Senator George J Mitchell Institute for Peace Security and Justice at Queen’s University, Belfast and at the Global Humanity for Peace Institute of the University of Wales Trinity St David. He has been recognized with many international prizes, honorary doctorates, and fellowships for his academic and practical contributions including the 2022 Lifetime Achievement Award from the Royal College of Psychiatrists and in 2024 Honorary Fellowship of the British Psychoanalytical Society.  Lord Alderdice is the Founding Chairman of The Concord Foundation.