The scene for discussing the sustainability of Estonian was set by early Estonian nation-builders’ – doctors Faehlmann (1843) and Kreutzwald (1857) – existentialist writings such as a foreword to the Estonian national epic „Kalevipoeg” (cf. Undusk 2004). While the endangerment of Estonian has been a topical issue for centuries already, there are no serious academic attempts of, except for a couple of Martin Ehala’s (2006; 2010; 2011) writings, judging its vitality and sustainability. The paper first sheds some light into the wilderness of ecolinguistic theory and then offers a new ecolinguistic approach which increasingly takes into account environmental factors of a language in question. The importance of environmental factors in studying the sustainability of a language was first highlighted by John Edwards (1992). Furthermore, the paper introduces a potential programme of studying the sustainability of Estonian within this new theoretical framework. Finally, the paper shortly presents the potential of applying agent-oriented modelling to sociolinguistic problems.