Nicholas Georgescu-Roegen (1971) educated economists on the notion of entropy laws in economics and ecological process. An earlier paper by Kenneth E. Boulding (1962) asked what we might do with a measure of organizational entropy, were one ever devised. The aim of this paper is to propose the notion of planning horizons as a candidate for this role. First, the concept of organizational entropy is discussed and defined within the interdependent domain of ecological economics. Next, the character and contributions of an entropic measure of organization are reviewed, as described in Boulding’s work. Third, the concept of planning horizons – and their relation to economic cohesion, efficiency and well-being – is introduced to show how ‘horizon effects’ (shifts in planning horizons) serve as an ordinal entropic measure of organization in dynamic complex settings of interdependent effects. Last, the promise of planning horizons as a new social research program in ecological economics shall be discussed.