The subject of AfT became a priority area of the Commonwealth Secretariat’s work programme on international trade immediately after it was formally discussed by WTO members at their Hong Kong Ministerial Conference in 2005. Since the establishment of the WTO’s role in monitoring AfT flows, the Commonwealth Secretariat’s work in the area, until now, has mainly focused on understanding effectiveness and impact. It has undertaken and commissioned several studies to assess the quantitative evidence. Along with the attempts made to examine the impact of both overall AfT flows and their various types, comparative effectiveness assessment has also been carried out by studying different groups of countries such as the small and vulnerable economies (SVEs) and Sub-Saharan Africa. This issue of Commonwealth Trade Hot Topics provides a summary of the key findings of a number of Commonwealth Secretariat-sponsored studies.