Solid formulation enhances the stability of biologics during storage by overcoming the challenges of biophysical and biochemical stability in the aqueous state. Fundamental investigations of protein structure and dynamics provide comprehensive insights into stabilization mechanisms at the molecular level. Protein stabilization in the glass state can be achieved through thermodynamic stabilization via water replacement and kinetic stabilization by limiting protein dynamics both locally and globally. The glass dynamics hypothesis, encompassing molecular motions relevant to solid-state proteins and dynamics pertinent to solid biologics, is thoroughly reviewed. Although characterization techniques for solid biologics formulations are limited due to their multi-component and amorphous nature, advanced highresolution biophysical techniques such as DES, NS, and ssNMR are employed to characterize protein motion in the solid state and its correlation with protein stability. Additionally, molecular attributes and formulation factors impacting protein stability should be considered when selecting excipients like sugar stabilizers, buffers, and surfactants. Furthermore, we have reviewed protein structure, protein-excipient miscibility, protein-excipient interactions, and physicochemical attributes such as microenvironmental pH, packing density, and interfacial stress and their impact on protein stability. Looking forward, it is critical to further investigate these mechanisms at different resolutions and time scales and directly measure protein-sugar interactions at the molecular level. These insights can guide the design of novel excipients, the rational selection of stabilizing agents, and facilitate the evaluation of the impact of the selection and optimization of drying processes.