A better understanding of the factors that determine the affinity for ligand-protein interactions remains an important goal in biophysical and medicinal chemistry. Three-dimensional structures reveal a significant amount of information about a complex, but these static structures only represent the lowest energy conformation. Molecules are mobile. Their conformational changes and internal dynamics are an integral part of their function. Linking these motions with architecture is not always straightforward, but is essential to understanding what drives the association between two molecules.