NMR spectroscopy and X-ray crystallography are currently the two most widely applied methods for the determination of macromolecular structures at high resolution. More recently, significant advances have been made in algorithms for the de novo prediction of protein structure, and, in favorable cases, the predicted models agree extremely well with experimentally determined structures. Here, we demonstrate a synergistic combination of NMR spectroscopy, de novo structure prediction, and X-ray crystallography in an effective overall strategy for rapidly determining the structure of the coat protein C-terminal domain from the Sulfolobus islandicus rod-shaped virus (SIRV). This approach takes advantage of the most accessible aspects of each structural technique and may be widely applicable for structure determination.