Abstract
In this note, we outline various possible long-run effects of an English-only acquisition policy in the European Union. The point of departure is how individual behaviour adapts to constraints in the environment. This leads to changes in collective behaviour, which becomes part of the environment, again influencing individual behaviour. Possible equilibria of this feedback mechanism are discussed. It is argued that domain loss and diglossia may result. The process is further characterized by external effects. Looking at language knowledge as a merit good, path dependencies and multiple stable equilibria can be explained.