This Oxford Handbook challenges basic concepts that have informed the study of sociolinguistics since its inception in the 1960s. In 27 chapters, the book challenges the modernist positivist perspective of the field that has treated languages and speech communities as bounded and the idealized native speaker as the ultimate authority. Instead, it offers a critical poststructuralist perspective that examines the socio-historical context that led to the emergence of dominant sociolinguistic concepts and develops new theoretical and methodological tools that challenge these dominant concepts. The contributors to this volume take this critical poststructuralist perspective as a starting point for engaging in explorations of a range of sociolinguistic topics including language variation, language ideologies, bi/multilingualism, language policy, linguistic landscapes and multimodality. Each of the contributors provides a critical overview of the limits of modernist positivist perspectives on their topic and offer ways of theorizing and researching their topic in ways that are aligned with a critical poststructuralist perspective. The book also provides a global perspective on these issues with contributors focused on North and South America, Europe, Australia, and Africa. Together, the interdisciplinary and global contributions reveal the limits of conventional approaches to sociolinguistics and offer a glimpse into directions for the future of the field.