Through his work, McMullen has campaigned for improvement in health, education, and access to human rights for
Indigenous Australians. From 2000 to 2014 McMullen led
Ian Thorpe's Fountain for Youth, focused on education in remote
Australian Aboriginal communities. The charity went into voluntary liquidation in early 2015, with remaining funds being redirected to AIME, the Australian Indigenous Mentoring Experience. McMullen was a director of AIME for 15 years, helping to grow Jack Manning Bancroft's education movement connecting university undergraduates as mentors for Aboriginal high-school students in urban areas. He was also a Director of Engineering Aid Australia, a philanthropic organisation whose primary initiative is the Indigenous Australian Engineering Summer School (IAESS) operating in
New South Wales as well as at
Curtin University in
Western Australia. IAESS aims to build opportunities for Aboriginal high school students to pursue tertiary studies and subsequently careers in engineering. In
North Queensland, McMullen worked with Jirribel
Aboriginal elder Ernie Grant on his holistic education project, described in
My Land My Tracks, and also with Grant's daughter, Sonya Jeffrey, in growing the cultural education project at Echo Creek, near
Tully. At
Beswick Falls, Northern Territory, McMullen was patron of the annual Walking with Spirits festival, staged by
Tom E. Lewis and
Djilpin Arts Aboriginal Corporation, which celebrates the ancient culture of Aboriginal people. He was a long-time friend of Lewis. In 2015,
Gurindji elders invited McMullen to deliver the annual
Vincent Lingiari Oration at
Charles Darwin University, honouring those who led the ongoing struggle for
Aboriginal land rights.
Aboriginal health As a founding trustee of the Jimmy Little Foundation, McMullen worked with
Jimmy Little and Aboriginal doctors and medical services to improve
kidney dialysis, as well as introducing "Uncle Jimmy's Thumbs Up" nutrition program, aimed at reducing and preventing
chronic illness in Indigenous communities. He has chaired the council meetings of the
National Aboriginal Community Controlled Health Organisation and joined their advocacy in federal Parliament. At prime minister
Kevin Rudd's 2020 Summit, McMullen was among the 100 people focussed on "
Closing the Gap" in Indigenous life expectancy, and improving the well-being of Aboriginal communities. He was founding patron of the
University of Canberra's Healthpact Centre developing health promotion and social equality programs, especially for Aboriginal children. ==Honours==