The “International Detection and Attribution Group” (IDAG) is a group of specialists on climate change detection and attribution who have been collaborating on assessing and reducing uncertainties in the estimates of climate change since 1995 and who have made substantial contributions to the Intergovernmental Panel on Climate Change (IPCC) process and the US Global Change Research Program (USGCRP) activities. This proposal seeks funds so that the group, with new members and leadership, will continue to combine results from individual members to arrive at a fuller understanding of the human contribution to climate change, with a particular focus on recent regional changes and impact-relevant variables; uncertainties in the estimates of that human contribution, and how these results reflect on predictions of future changes and their impacts. Funding is for coordination, organization of annual meetings, writing of synthesis and review documents. The results from this integrative work will be much more valuable than the sum of its parts, and we expect it to feed into new IPCC and US assessments, including the IPCC 5th Assessment that will be published in stages in 2013 and 2014. We will also continue to make the expertise of the group available through input to agencies and timely and influential review papers.