The accumulation of relevant and appropriate data is the essential preliminary to any successful informatics-based exercise in prediction. Without quality data, meaningful prediction is impossible. This is as true in immunobiology as it is in any other branch of the natural sciences. Within the context of vaccine discovery, the accumulation, storage, and retrieval of immunological data within publically accessible repositories, typically web-based databases, is of overwhelming operational importance. Specifically, and with the special reference to the discovery of subunit vaccines, this chapter explores the current state and status of immunological databases focussed on immunogenic proteins, primarily pathogen antigens and environmental allergens. It sets this exploration firmly into context by simultaneously scoping out the rather more mature backdrop provided by epitope-orientated database systems.