This book is the result of my long-standing involvement with pluricentric languages, which for me personally began in 1980. It was mainly the many works by Michael Clyne that brought about a lasting change and helped the concept of pluricentricity to break through. Encouraged by Michael Clyne's support, the 'International Working Group on Non-dominant Varieties of Pluricentric Languages' (WGNV) was founded in 2010 at the Pluricentric Conference organised by Augusto Soares da Silva in Braga, Portugal. In 2011 I organised the first WGNV conference, the papers of which were published in an edited volume. A total of 10 WGNV-conferences have been held since 2011, and the 11th conference will take place in May 2025 in Lisbon. Since 2011, 233 papers by 299 authors have been published. This book is an attempt to summarise the theory of pluricentricity and to reflect the current state of the discussion. In doing so, I rely on my own work as well as on that published in the context of the WGNDV conferences and others. Of course, relevant work by other researchers has also been included. The book is intended to help clarify key questions of pluricentricity and promote the further development
