This volume presents a paradigm shift in the world's knowledge about children's speech development, with 80 chapters covering 75 languages and language varieties or dialects from across the globe. Each of the chapters follows the same structure, facilitating comparison across languages and dialects. Researchers and students can identify relationships between common and unique elements of children's speech to develop new theories and enhance understanding. Crucially, the curated data in the chapters can be used by communication specialists to collaborate with families and communities, in order to support children's home language maintenance and speech development, including in languages not spoken by the specialists. The Oxford Handbook of Speech Development in Languages of the World outlines a transformative approach by which the discipline can overcome traditional English- and Western-centric biases by respecting and acknowledging longstanding traditions of research, theories, and knowledge from a wide range of countries and cultures - including knowledge not previously translated into English. Languages spoken by First Nations people and traditionally marginalized groups are given equivalent status to majority languages, and the language maps, resources, and pronunciation guides have been created using a rights-based, social justice approach, acknowledging the impact of colonization.