He is a graduate of Panteion University and holds an MA (1985) and a PhD (1989) in International Relations and Comparative Politics, from the School of International Service, American University, Washington DC, both with honors.

He has been Lecturer on International Relations and Comparative Politics at the School of International Service at the American University (1987-89), Post-doctoral Fellow at the Center for European Studies at Harvard University (1990-92), and Assistant Professor of Government and European Politics at the Department of Public and International Affairs at George Mason University (1992-95). In 1995 he became Assistant Professor of International Relations at the Department of International and European Studies at Panteion University, in Athens, Greece. In 2008 he became Professor at the same Department. He chaired the Department from 2006 to 2010. Beginning September 2019 and for three consecutive years he was the "Constantine G. Karamanlis" Chair in Hellenic and European Studies at Fletcher School of Law and Diplomacy at Tufts University in Boston, USA.

His research interests are in International Relations Theory, Political Theory, European Politics and US Foreign Policy Analysis. He has taught courses on theory and methodology of International Relations, European Politics, and Comparative Analysis.

He has published articles on the EU, the non-aligned movement, Greek-Turkish relations, the study of leadership and authoritarian regimes. He has written books on the transitions from authoritarianism to democracy, on transatlantic relations, on US foreign policy and a textbook on international relations. His latest book is entitled "The Transatlantic Partnership at a Crossroads: Renewal or Decoupling".