The Welsh language, which is indigenous to Wales, is one of six Celtic languages. It is spoken by 562,000 speakers, 19% of the population of Wales, according to the 2011 U.K. Census, and it is estimated that it is spoken by a further 200,000 residents elsewhere in the United Kingdom. No exact figures exist for the undoubted thousands of other Welsh speakers beyond the United Kingdom who are able to communicate in Welsh as migrants to other European countries, members of the Welsh diasporas in North and South America, Australia, and Southern Africa; and language learners elsewhere. The subject of this chapter is a sometimes mysterious, often idiosyncratic process, which always involves struggle, sacrifice, and tension. Language revitalization is an attempt to counter trends that have influenced decline in the use and learning of the language. The pressures typically are a combination of historical conquest, political and economic control, and deep psychological hurt whereby a former relatively autonomous group are subjugated into a dependent people whose prime markers of distinction, such as language or religious differentiation, are eroded, made illegal, or otherwise eradicated from formal public life. At various periods in West European history, this has been the fate of Welsh, Irish, Gaelic, Breton, Basque, and Catalan, among others. Thus, at root, language revitalization speaks of a much deeper and significant historical trend, the attainment of an element of cultural and popular autonomy within salient historical domains such as public education, local government, and community development. Language revitalization is a conscious effort to change ideas, values, attitudes, and behaviors. The author of this article concludes that if the Welsh example of language revitalization teaches us anything, it is that stubborn collective action by the community must be stimulated before government language policy responds in a reactive manner, but having so responded, that community engagement must also be maintained, for fear of losing direction and long-term momentum (Williams, 2007a, 2007b).