3D electron diffraction (3DED) was used to elucidate the structure of a new ninth polymorph of indomethacin from an amorphous solid dispersion, which are product formulations used to improve the dissolution performance of active pharmaceutical ingredients with poor aqueous solubility. Insights from the structure solution allowed for a simpler crystallization route for this polymorph to be deduced, demonstrating the relevance of 3DED within drug development.