Abstract: The Yearbook for Direct Democracy 2021 contains three essays. From a political science perspective, these deal with the possibilities of making vote manipulation visible, and from a jurisprudential perspective, with the formation of opinion through social media in the advance of referendums. The third contribution examines the instrument of the “Volkseinwand” discussed in Thuringia. Four further contributions report on recent developments in Switzerland, Germany, Austria and the USA. The overview of case law includes key decisions on direct democracy. Two documentations, a list of new literature and a review complement the Yearbook. <bold>With contributions by</bold> Prof. Dr. Nadja Braun Binder; Prof. Dr. Daniel Bochsler; Prof. Dr. Lars P. Feld; Prof. Dr. Hermann K. Heußner; Dr. Eike-Christian Hornig; Prof. Dr. Peter M. Huber; Anna-Lia Käslin-Tanduo; Julian Marbach, MLaw; Prof. Dr. Arne Pautsch; Prof. Dr. Klaus Poier; Frank Rehmet; Prof. Dr. Axel Tschentscher; Martin Wittmer, MLaw and Prof. Dr. Fabian Wittreck.