Metslang studied Estonian philology at the University of Tartu, graduating in 1974.
In 1978 she defended her candidate thesis on syntactic aspects of Estonian folk poetry.
[1] She received her doctoral degree at the University of Oulu in 1994 for a comparative study of Estonian and Finnish.
[2][1] Metslang has been the recipient of numerous national and international awards, including the Wiedemann Language Award (2020), an honorary doctorate from the University of Tartu (2020), and the Grand Medal of the University of Tartu (2020).
[1][2] Along with Mati Erelt and Reet Kasik she is one of the lead authors of Eesti keele grammatika, the main current descriptive grammar of the Estonian language.