Investigations of language use in multilingual regions are traditionally done through the usage of retrospective questionnaires, either distributed on paper, or digitally. The aim of the present study was to test a new method of measuring language choice and use: by using social media to contact individuals several times a day and ask them what language(s) they are using, how, and with whom. It was investigated whether this method could provide real-time data on an individual's language use. One hundred participants living in the Netherlands were given a language background questionnaire and were asked to provide information through Facebook®. It was found that the social media data generally reflect the questionnaire data. More importantly, the social media data include more exact information on cases of codemixing and allow to compile a typology of language contact situations. It was concluded that social media inquiries could prove useful in future language use studies. Methodological issues, in particular concerning privacy and problems related to crowd sourcing of language data through social media, are discussed.