He teaches at the University of Otago in modern Irish history and has published widely on New Zealand's ethnic and religious past.
He received his secondary education at St Peter's College, Auckland, New Zealand.
[2] He has history degrees from Trinity College Dublin (BA (Hons) 1981) and Peterhouse, Cambridge (Ph.D., 1991).
[3] Sweetman's doctorate from Cambridge University was on the subject, New Zealand Catholicism, War, Politics and the Irish Issue 1912-22.
[4] He has written a number of institutional histories including a history of Otago Boys' High School which was published in 2013 in relation to its sesquicentennial[5][6] and, more centrally to his academic interests, Defending Trinity College Dublin, Easter 1916: Anzacs and the Rising.