Mass spectrometry offers a new perspective on the solution and gas-phase properties of viruses. Its broad application to local and global viral structure provides unique insights into many biological processes, including viral-antibody binding, protein-protein interactions and protein dynamics. Mass measuring viral proteins is now routine and since viruses are typically well characterized, in that the capsid proteins and DNA (or RNA) sequences are known, identifying a virus based on the mass of the protein and enzymatic digestion fragments is relatively straightforward. Using mass spectrometry, this paper describes the identification of viral protein post-translational modifications such as myristoylation, phosphorylation and disulfide bridging. Furthermore, complementary data obtained with mass spectrometry and x-ray crystallography demonstrate that viruses are highly dynamic particles whose viral capsid's mobility could, until recently, be inferred only from inherently static spectroscopic methods. Lastly, mass spectrometry has been applied on a global scale via the mass measurement of entire intact viruses. Given the general utility of mass spectrometry, its continuing development should further its application to viral dynamics, structure, function and identification.