From 1978 to 1985 Ruth worked as a library and publishing company employee, and from 1986 to 1989 as a translator from Lithuanian and Polish. Between 1990 and 1996 Ruth studied Medieval, Modern and Contemporary History and Polish Studies in Berlin and Vilnius. In August 1996 she received her Master of Arts, and a PhD  from Humboldt University of Berlin in November 1997. She joined the Institute of Westlitauische and Prussian History, University of Klaipeda, as a lecturer in 1995, and between 1996 and 1999 was a researcher at the Thomas Mann Cultural Centre in Nida. From 1997 to 2000 Ruth was editor of the Bosch Foundation at the Institute of Westlitauische and Prussian History, University of Klaipeda, and from 2001 to 2003  researcher at the Institute of History of the Humboldt University of Berlin (project of the Fritz Thyssen Foundation). Between 2005 and 2008 Ruth was Project Coordinator of the DFG project "NBI Nation Borders Identities" on BKVGE Berlin, and to 2009 researcher at the Institute of History and Archaeology of the Baltic Region (BRIAI) University Klaipeda. In October 2007 she received her Habilitation and Venia legendi for acquisition of Eastern European History at the Humboldt University of Berlin. Since October 2009 Ruth has been Deputy Director at the GHI Warsaw.