The aim of this paper is to introduce an overall approach to control crystal morphology. The habit changes of organic crystals are studied by means of additives. Discussion follows on (1) the way to calculate theoretical morphologies, (2) the choice of suitable additives able to modify morphologies in the required way, and finally, (3) the determination of the experimental conditions for best use of the proposed additives, Adipic acid is chosen as a model substance to illustrate the method developed.