Although many virus proteins are glycosylated, the pattern of glycosylation that is exhibited can be highly variable, and it is largely dependent on how a specific virus protein is processed by the host cell during infection. However, irrespective of their glycosylation pattern, many virus glycoproteins have been found to play essential roles during the virus replication cycle. Consequently, it is therefore becoming necessary to understand the effect that the attached glycans have on the function of different virus glycoproteins. As a first step towards understanding how glycans can influence the activity of a specific glycoprotein, we need to both establish the mechanism of glycosylation, and determine the nature of the attached glycans. This chapter provides an overview of some of the different ways in which viruses proteins are glycosylated, and highlights some of the generic techniques by which they can be examined.