Virtual professional communities require a strong co-evolution of their social and information systems. To ensure that the evolutionary process of their socio-technical systems is viable, a legitimate user-driven specification process is required. Such a process helps to ensure the meaningfulness and acceptability of specification changes. A specification method supporting this process should be grounded in the neo-humanist paradigm so that subjectivist and conflict aspects receive proper attention. Two related subfields of information science that have roots in this paradigm are the Language/Action Perspective (LAP) and organisational semiotics (OS). The RENISYS method for specification of the socio-technical systems of virtual professional communities is presented. It combines aspects from both LAP and OS, by building on work done in the DEMO (LAP) and MEASUR (OS) methodologies. It thus provides an operationalization of neo-humanist ideals that can help to extend theoretical and empirical research.