Jan Rijkhoff is Associate Professor of Linguistics at Aarhus University in Denmark. His books include The Noun Phrase (OUP 2002) and, with co-editor Daniel Garcia Velasco, The Noun Phrase in Functional Discourse Grammar (Mouton de Gruyter 2008). He has published on numerous topics - including word classes - in various international journals, including Journal of Linguistics, Linguistic Typology, Language and Linguistics Compass, Journal of Semantics, Linguistics, and Studies in Language.Eva van Lier is a Postdoctoral Research Fellow in Linguistics at the University of Amsterdam. Her publications include several journal articles on word class typology and the monograph Parts of Speech and Dependent Clauses: a typological study (Utrecht: LOT 2009). Currently she investigates properties of flexible word classes in Oceanic languages with a grant from the Netherlands Organisation for Scientific Research (NWO).