In this work, the thermodynamic and kinetic aspects of D-mannitol's three polymorphs and their transformations are addressed. Scalable and reproducible syntheses of the solid-state forms are presented, and a mathematical model to describe a three-polymorph transformation is discussed in detail. It is shown that, for certain initial solute concentrations, the a polymorph nucleates first and then transforms through the beta form to the gamma form. Moreover, a supersaturation threshold to nucleate the a form has been observed, and below this threshold value, the gamma form nucleates. A theoretical analysis demonstrates that this behavior can be predicted and that this experimental observation is physically sound.