This dictionary, with more than 1000 articles, provides a comprehensive survey of all important aspects of Celtic religion and culture, covering both the prehistoric continental Celts and the later, medieval culture that found written form long after the Celts had settled in the British Isles. Articles in the dictionary also cover the interaction between Celtic and Roman civilisations, and the seminal input of medieval Celtic legend into the Arthurian tradition. The continental and insular Celtic languages, both ancient and modern, are described, and there is a full account of the Celtic deities known to us from the inscriptions and iconography of the classical world. Celtic art and agriculture, the Ossian myth, the Irish Renaissance, and the history of Celtic studies are among other areas treated in depth.