Bettelou Los is a linguist and philologist specializing in the history of the English language.
Since 2013 she has held the Forbes Chair of English Language at the University of Edinburgh.
After spending some time working as a translator, she obtained her PhD in 2000 from the Vrije Universiteit Amsterdam; her dissertation focused on infinitives in Old and Middle English.
Information structure and its interaction with syntactic change has played an important role in her more recent work.
Her book on the rise of the to-infinitive in English is the standard reference on that subject, and she has also carried out important work on discourse adverbs, particles, and verb-second, among other topics.