The solid form (polymorph, hydrate, solvate, salt, cocrystal or amorphous solid) of an API can greatly influence its thermodynamic, kinetic and particulate properties. Establishing the prevalence of a low energy form and the polymorph landscape around that form is important for assessment of developability but also reproducibility in subsequent scale up of isolation and in performance characteristics in the formulation. Adequate solid state characterization with orthogonal methods such as DSC, XRPD, TGA, Raman spectroscopy, microscopy, and solid state NMR, is a routine part of developing form understanding. Proper characterization and solubility analysis of early drug substance lots used in tox studies can also aid in setting direction for process improvements or form enablement.