Prof McCallum is an academic leader widely published in peer-reviewed publications, books and monographs; NHMRC evidence statements and Guidelines; National Seniors reports. He had teaching and research roles at: Griffith University; Andrus Gerontology Center University of Southern California; Nanzan University Nagoya; Tokyo Metropolitan Institute of Gerontology; Renmin University Beijing; ESCAP Bangkok; Ageing Family Project; National Centre for Epidemiology and Population Health ANU from where he ran the Dubbo Study of the Health of the Elderly.

He was Executive Dean Health and Social Sciences University of Western Sydney (received Campbelltown Council Community Service Award), Senior Deputy Vice Chancellor and Director TAFE Victoria University; Senior Executive (NHMRC Research Translation Group; Director NHMRC National Institute for Dementia Research; Research Director National Seniors Australia and CEO from 2018.

Some of his major projects were: Dubbo Longitudinal Study of Ageing, Australia-Japan Collaboration in Aged Care, Asset and Health Dynamics of the ‘Old’ Old (AHEAD), Vietnam Veterans Mortality Study and he received the Federation Medal in 2003 ‘for outstanding service as a researcher to ageing and aged care issues’.