The Paris Declaration, endorsed in March 2005, by over one hundred Ministers and Heads of Agencies lays down a roadmap to improve the quality of aid and its impact on development. An independent, multi-phased and cross-country evaluation of the Paris Declaration was initiated in 2007. The first phase comprised 20 separate but coordinated evaluations in donor countries and developing countries. A Synthesis of these evaluations was published in June 2008. The second phase comprised 28 evaluations of donors and developing countries. It was conducted during 2010 - 11 and the report published in June 2011. The focus of phase 2 is on the effects of the Paris Declaration on aid effectiveness and development results. This is one of the hitherto largest joint evaluations undertaken applying a unique decentralized approach employing more than 150 evaluators from 30+ countries. The Panel presents the results of the evaluation and lessons learned from the approach. #2011Conference #InternationalandCross-CulturalEval