<p>The book <i>Epistemological and Theoretical Foundations in Language Policy and Planning</i> explores the diverse epistemological and theoretical perspectives that are used in language policy and planning. It presents a wide-ranging overview, covering basic concepts through to cutting-edge implementations. The book addresses a broad spectrum of topics, such as the social dimensions of language planning, the impact of public policies on language use, contemporary strategies for corpus planning, and the combination of language policy and planning with technology to rejuvenate endangered languages. Additionally, it examines the connections among language policy, theoretical linguistics, and natural language processing, emphasizing the need to engage linguistic communities in creating language technologies that tackle linguistic disparities in the digital era. This exploration delves into each aspect of the themes in order to provide rich perspectives on both theoretical and practical works being performed within the domain.</p>