Dennis is the director and co-founder of Feedback Labs, which is supported by a number of the world's leading foundations. He is also co-founder of GlobalGiving, where he was CEO from 2000 to 2010. From 2013 to 2015, Dennis was the Executive Chairman of Ashoka Changemakers. He also recently completed terms as a Professor of the Practice and Social Entrepreneur in Residence in the Economics Department at UNC-Chapel Hill, Visiting Fellow at the Center for Global Development, and Visiting Lecturer at the Woodrow Wilson School at Princeton University. Earlier in his career, he spent fifteen years as an economist working in developing countries at international organizations and multilateral aid agencies. In the late 1990s, he was Senior Partner and Principal Economist of the World Bank's Strategy and Innovation Group, where his team created the Innovation Marketplace and Development Marketplace. He also worked for the World Bank in Africa, Indonesia, and Russia, where he managed a wide range of agriculture, housing, energy efficiency, and structural reform projects.