Virtual organizations are perceived as a means for achieving flexibility. However, shared inter-organizational business processes may pose additional constraints on the internal processes of an organization and reduce their flexibility. The paper builds on a conceptual model of business processes in a virtual organization. The model aimes at identifying a minimal process definition to support the collaborative process while allowing flexibility of the internal processes. The model is informally presented through a case study of an inter-library loan process, and its implications on flexibility are discussed.