Senior Fellow at the German Institute for International and Security Affairs (SWP), Head of the Global Issues Research Group there until 2021, leading research projects on German, European and international refugee and migration policy and on demographic developments. 2011-2014 Advisor at the Federal Ministry for Economic Cooperation and Development. 1993-2006 Researcher and advisor to the German Council on Foreign Relations (DGAP) and editor of the Yearbook on International Affairs.

2001 member of the Independent Commission on Immigration of the Federal Government (Süssmuth Commission) and 2004 member of the Expert Council on Immigration and Integration of the Federal Government (Immigration Council); 2020/21 appointment by the Federal Government to the Independent Expert Commission on the Root Causes of Forced Displacement.

In addition to the Federal Government and the Bundestag, advisor to Diakonisches Werk, Caritas, UNICEF, UNHCR, International Federation of Red Cross and Red Crescent Societies, International Organization for Migration (IOM), Council for Asia-Europe Cooperation (CAEC), EU Commission, National Population and Family Planning Commission (NPFPC) of the People’s Republic of China, World Bank, Global Forum on Migration and Development (GFMD), International Centre for Migration Policy Development (ICMPD).