Associate Professor David Mackenzie is the founding CEO of Upstream Australia Ltd, a not-for-profit field-building intermediary organisation advocating for place-based collective impact system change and a backbone support platform supporting funded and yet-to-be-funded COSS Model communities. David has undertaken research and development over more than 30 years focused on young people’s issues and social policy, homelessness and social and educational disadvantage. With Chris Chamberlain, he formulated the influential Australian cultural definition of homelessness and developed the methodology for estimating homelessness in Australia that has been adopted by the Australian Bureau of Statistics. In 2007-2008, he was one of the four commissioners responsible for the National Youth Commission Inquiry into Youth Homelessness [NYC] and the influential report Australia’s Homeless Youth. He currently holds an adjunct position at the University of New South Wales.