[en] Transitions are societal transformation processes that occur in at least one generation (i.e. 25 years). Transitions are structural changes of the society or a complex part of that society. Transitions show technological, economical, ecological, socio-cultural and institutional developments on different levels. A transition is the result of slow changes (developments in supplies) and fast dynamics (flows). In general, four transition phases can be distinguished: (1) a pre-development phase of dynamic equilibrium in which the status quo does not change much; (2) a take-off phase in which the process of change is started; (3) an acceleration phase in which structural changes occur, resulting in collective learning processes, diffusion and processes of implementation; (4) a stabilization phase in which the speed of societal changes decreases and a new dynamic equilibrium exists. Within the framework of the preparatory process of the Fourth Dutch National Environmental Plan (NMP4) a study has been carried out to explore the transition concept, focusing on an emission-low energy supply in the Netherlands. 49 refs