Sebastián Valenzuela (PhD, School of Journalism, University of Texas at Austin) is Associate Professor and Director of Research in the School of Communications at the Pontifical Catholic University of Chile, and Associate Researcher with the Millennium Institute for Foundational Research on Data (IMFD) in Chile, where he leads the mis/disinformation interdisciplinary research group.

He is associate editor for the International Journal of Public Opinion Research, and sits on the editorial board of several top-tier journals in communication, including Digital Journalism, Journal of Communication, and the International Journal of Press/Politics. He is an expert in political communication, journalism and social media, topics on which he has authored more than 70 peer-reviewed publications, including the third edition of Setting the Agenda: The News Media and Public Opinion (Polity Press, 2021). His research has been awarded by the International Communication Association (ICA), the Association for Education in Journalism and Mass Communication (AEJMC), and the World Association for Public Opinion Research (WAPOR), and has been featured in international publications such as the BBC, The New Yorker, Time and the Wall Street Journal.

He has done consulting work on mis/disinformation for the United Nations Development Program and two fact-checking projects in Chile (Contexto Factual and Fact Checking UC). He has held visiting research positions at the universities of Wisconsin-Madison (School of Journalism & Mass Communication) and Amsterdam (ASCoR). Previously, he was a Fulbright scholar and a journalist for El Mercurio newspaper in Santiago, Chile.