Joseph F. Eska is Professor of Language Sciences in the Department of English at Virginia Polytechnic Institute & State University, USA.  Silva Nurmio is an Academy Research Fellow in the Department of Languages at the University of Helsinki, Finland. Peadar Ó Muircheartaigh is Senior Lecturer in the Department of Celtic and Scottish Studies at the University of Edinburgh, UK. Paul Russell is the Margaret Brooks Robinson Professor of Celtic Languages and Literatures in the Department of Celtic Languages and Literatures at Harvard University, USA.

• Introduction.- I- Modern Brittonic.- The phonology of Modern Breton.- Initial consonant mutation in Modern Breton.- The morphology of Modern Breton.- The syntax of Modern Breton.- The phonology and phonetics of Modern Welsh.- Initial consonant mutation in Modern Welsh.- The morphology of Modern Welsh.- The syntax of Modern Welsh.- The dialects of Modern Welsh.- A practice-based approach to the documentation of a heritage language. Speaker profiles and varieties of Breton.- The sociolinguistics and social situation of Revived Cornish.- The sociolinguistics and social situation of Breton.- The sociolinguistics of Welsh.- Welsh-English and Welsh-Spanish bilingualism.- II- Modern Goidelic.- The phonology and phonetics of Modern Irish.- The initial mutations of Modern Irish.- The morphology of Modern Irish.- The syntax of Irish Gaelic.- The phonology and phonetics of Scottish Gaelic.- The morphology of Scottish Gaelic.- The syntax of Scottish Gaelic.- The phonology of Manx.- The morphology and syntax of Manx.- The language of Early Modern Irish.- The Gaelic languages. Dialect and register variation.- Intergenerational transmission of the Gaelic languages. Decline and renewal.- Emergent Gaelic varieties.- Irish and Scottish Gaelic language technology.- Revived Manx.- III- Medieval Insular Celtic languages.- Sources for medieval Celtic languages.- The orthography of the medieval Celtic languages.- The historical origin of the Insular Celtic mutations.- IV- Medieval Brittonic.- The phonology of medieval Breton.- The morphology of medieval Breton.- The syntax of medieval Breton.- The phonology of medieval Cornish, 900–1800.- The morphology of medieval Cornish.- The syntax of medieval Cornish.- The phonology of medieval Welsh.- The morphology of medieval Welsh.- The syntax of medieval Welsh. Word order and information structure.- Pictish and Cumbric.- Comparative Brittonic phonology.- Comparative Brittonic morphology.- Comparative Brittonic syntax.- V- Medieval Goidelic.- The phonology of Old Irish.- The morphology of Old Irish.- The syntax of Old Irish.- The transition from Old to Middle Irish.- VI- Continental Celtic.- The sources for Continental Celtic.- The scripts and orthography of Continental Celtic.- The phonology of Continental Celtic.- The morphology of Continental Celtic.- The syntax of Continental Celtic.- VII- Language relationships.- The interrelationships of the Celtic languages.- Italo-Celtic preverbs and adpositions.