The development of mechanistic insight into the molecular basis of how intrinsically disordered proteins function is a key challenge for contemporary molecular biology. Intrinsic protein disorder is abundant in the replication machinery of paramyxoviruses. In order to study this kind of protein, new methods are required that specifically take account of the highly dynamic nature of the chain, and describe this disorder in quantitative terms. Here we review recent studies of conformational disorder in paramyxoviral phosphoproteins and nucleoproteins using solution-based approaches such as nuclear magnetic resonance.