de Jong (born 22 June 1947, The Hague) graduated in General Linguistics, French and English languages from Leiden University and obtained a PhD in Educational Measurement from Twente University.
[1] He has published many articles and books on language acquisition and assessment and on educational measurement.
He was involved from the start in developing the Common European Framework of Reference for Languages.
After teaching French for seven years, de Jong continued his career at CITO, the Dutch National Institute for Educational Management.
In 2016 De Jong received the Cambridge/International Language Testing Association Distinguished Achievement Award.