Macklin was a researcher at the Australian National University in 1976–78, an economics research specialist with the Parliamentary Library in Canberra 1978–81, Research Coordinator at the Labour Resource Centre in Melbourne 1981–1985, an adviser to the Victorian Minister for Health 1985–88, director of the federal government's National Health Strategy 1990–93 and director of the Australian Urban and Regional Development Review 1993–1995.