He gained his BA in Economics from the University of Cambridge (MA 1970) and his doctorate at the University of Amsterdam. He was a Frank Knox Memorial Fellow (1966-67) at Harvard University. After returning from America, he taught at the University of Exeter, England, from 1967 to 1990, when he became Professor of Sociology in the Department of Anthropology and Sociology at Monash University in Australia, before returning to Europe as Professor at UCD in 1993. He retired in 2009.
At UCD, along with his wife Barbara, he founded UCD Press on behalf of the university, serving as Chairman of its Editorial Committee 1995–2006. He also served as first Director (1999–2002) of what is now the Geary Institute, a new social scientific research institute established with Irish government support.
Stephen Mennell's major intellectual influence is Norbert Elias, and since 1997 he has been a member of the Board of the Norbert Elias Foundation, Amsterdam - in effect one of Elias's executors. He is General Editor of the Collected Works of Norbert Elias in English, publication of which in 18 volumes by UCD Press began in 2006 and was completed in 2014.
Elias's influence is especially evident in Mennell's book All Manners of Food: Eating and Taste in England and France from the Middle Ages to the Present (1985), and in The American Civilizing Process (2007). His other books include Sociological Theory: Uses and Unities (1974; rev. edn 1980), Alexis de Tocqueville on Democracy, Revolution and Society (edited with John Stone, 1980), and two selections of Elias's writings edited with Johan Goudsblom. In 2011 he was elected President of the International Sociological Association's new Working Group 02: Historical and Comparative Sociology.
Stephen Mennell was awarded the degree of Doctor of Letters by the University of Cambridge in 2004. He was elected a Member of the Royal Netherlands Academy of Arts and Sciences in 2004, of the Royal Irish Academy in 2009, and of the Academia Europaea in 2011.
From 2010 to 2016, he served as President of Working Group 02, Historical and Comparative Sociology, of the International Sociological Association; in 2016 this was upgraded to the status of a full Research Committee, under the title RC 56, Historical Sociology.
On 7–8 January 2016, a conference on the theme of 'Social Character and Historical Processes' was held in Dublin in Stephen Mennell's honour: see the conference programme and his outline of his own intellectual development. A selection of the papers presented at this conference was published in the online journal Human Figurations 5: 2 (2016).