Organisations have to adapt rapidly to survive in today’s diverse and rapidly changing environments. The idea of virtual organisations emerged as an answer. There is a strong need to understand virtual organisations (VOs) in a formal way: changes can have side effects and hence one might wish to understand precisely what consequences a change might have. The Virtual Organisation Modelling Language (VOML) consists of sub-languages to model different aspects of VOs such as their structure or operational models: VO-S deals with structural aspects while VO-R addresses reconfigurations. The concepts are exemplified through a travel booking VO that needs to cope with extra demands imposed by a large event such as the Olympic games.