Legacy information systems are often part of an organisation’s assets. Some of them play an important role in serving the organisation. From time to time, however, there is a need to improve these information systems to produce a better performance or better interoperability with other systems. It is sometimes necessary to re-engineer these systems. Organisational semiotics and methods have been used in such applications. This chapter illustrates an organisational semiotics approach to legacy systems re-engineering in a university library in which the three key Methods for Eliciting, Analysing and Specifying Users’ Requirements methods – the problem articulation method (PAM), semantic analysis method and norm analysis method – were applied.