The aim of this paper is to give a long term sustainability perspective on instrumentation in environmental policy, within a broad, also strategic, evaluative framework. To arrive at integrated insight, the basic function of policy instruments is discussed: why do you need them at all and how would they look like? It comes out that it is not at all clear how policy instruments can be classified and described. Nor is it clear how a consistent evaluation of policy instruments can be set up. Still, as some ordering is necessary for instrument development and instrument choice, an analytic framework is developed. One basic problem in discussions on policy instruments is that both their functioning and their effects are context dependent. This implies that in decisions on policy instrumentation, binding society for a long time, also long term changes in context are to be taken into account, in terms of structural, cultural and economic developments in society. Some main lines of development are discussed, with implications for instrument choice. Within these mouldable boundaries, some practical guidelines are given for policy development at a case level.