On December 12 our colleague Zohreh Zahedi successfully defended her PhD dissertation entitled “Understanding the Value of Social Media Metrics for Research Evaluation”. Zohreh’s PhD research at CWTS was supervised by Paul Wouters and Rodrigo Costas, and was defended in a ceremony celebrated at the Academic Building of Leiden University. The opposition committee consisted of Sarah de Rijcke (Leiden University), Thed van Leeuwen (Leiden University), Mike Thelwall (University of Wolverhampton), Isabella Peters (University of Kiel), Cassidy R. Sugimoto (Indiana University Bloomington), Pedro Russo (Leiden University) and Cornelis van Bochove (Leiden University). Zohreh’s dissertation extensively discusses the value and usefulness of different social media metrics for research evaluation, highlighting in particular the relevance of Mendeley readership statistics in the future of academic evaluations. CWTS congratulates Zohreh on this important achievement and her valuable contributions to the field of scientometrics.