In the first decade of the current century Australia experienced a huge increase in net international (overseas) migration. All demographic forecasts failed to predict this change. The aim of this paper is to assess past net overseas migration forecasts for Australia to quantify the extent of the forecasting challenge, and suggest ways in which improvements might be made. Official net overseas migration forecasts for the past four decades were assessed against subsequently published migration estimates. Mostly they proved highly inaccurate, both for individual years and cumulatively over longer periods. It is suggested that: (1) greater use be made of a detailed migration data source which provides migration estimates by visa/citizenship category, and (2) a combined migration forecasting approach, which draws strength from several complementary methods, is developed. Progress in these two areas offers the potential to improve the accuracy and utility of Australia’s overseas migration forecasts.