In 2014-2015, she participated in the prestigious Leadership and Education Innovation Programme at the Center of Excellence in University Teaching (Utrecht University). In 2015, she was nominated for the VU Education Innovation Prize.

Hagen's research focuses on the connection between culture and politics during the revolutionary period in the Netherlands (1780-1815). Her qualitative and biographical approach reflects a particular historical interest in human agency and the individual, as evidenced by people’s changing practices, emotions and attitudes toward power and political authority. Her work highlights revolutionary efforts to reshape cultural norms about femininity, masculinity, gender and power relations, as well as religious and civic virtues and national identity.

Hagen is inspired by a wide range of sources, from democratic print culture and parliamentary papers to clothing and portraits and political expressions in ‘ego documents’ (writings such as personal letters, autobiographies, diaries), theatre plays and novels. Hagen’s PhD on Dutch Enlightened and Protestant Anti-Papism around 1800 received national coverage by the Dutch press and was praised by historians as ‘an exemplary dissertation’ (Professor Emeritus G.J. Schutte) and ‘Darntonian’ (Professor Emeritus A.W.F.M. van de Sande).

Articles by Hagen on the image-creation and emotional self-fashioning of Dutch revolutionaries have been published in peer-reviewed journals, as well as in popular historical magazines. In 2012, she attracted nation-wide media attention for her well-received Libris History Prize nominated political biography on the statesman Rutger Jan Schimmelpenninck (1761-1825) and his wife Catharina Nahuys (1770-1844). As one of the contributors to the Routledge Handbook of Character Assassination and Reputation Management , she is currently working on tactics for reputation management by presenting a case study on the Dutch revolutionary Adam Gerard Mappa (1754-1828).