Book excerpt: Heritage languages are minority languages learned in a bilingual environment. These include immigrant languages, aboriginal or indigenous languages and historical minority languages. In the last two decades, heritage languages have become central to many areas of linguistic research, from bilingual language acquisition, education and language policies, to theoretical linguistics. Bringing together contributions from a team of internationally renowned experts, this Handbook provides a state-of-the-art overview of this emerging area of study from a number of different perspectives, ranging from theoretical linguistics to language education and pedagogy. Presenting comprehensive data on heritage languages from around the world, it covers issues ranging from individual aspects of heritage language knowledge to broader societal, educational, and policy concerns in local, global and international contexts. Surveying the most current issues and trends in this exciting field, it is essential reading for graduate students and researchers, as well as language practitioners and other language professionals.