Grin studied economics at the University of Geneva, where he obtained a doctorate summa cum laude in 1989. He then was a teacher at the universities of Montreal and Washington (in Seattle), assistant professor at the University of Geneva and vice-director of the European Centre for Minority Issues in Flensburg, Germany. Since 2001 he is a visiting professor at the University of Lugano, in 2003 he became professor at the University of Geneva.
In his research, he studies the linguistic situation in Switzerland and in the European Union and its economic consequences. He is the author of a 2005 report entitled L'enseignement des langues étrangères comme politique publique (The teaching of foreign languages as a public policy), best known as the Grin Report. In this document, Grin indicates that the choice of Esperanto as a bridge language for Europe would lead to an annual saving of 25 billion euros. He also suggested a language tax to compensate for the drawbacks of countries whose language is not widespread.
Grin has also studied the case of Kalmyk, a minority language in Russia.