This study focuses on individuals working under transient and mobile conditions and the specific competences that they develop to deal with such work conditions. The article examines a specific type of knowledge worker, namely, the mobile project worker who is employed by a technical consultancy but who performs work on various client projects together with members from client organizations. The overall aim of this article is to improve our understanding of the differences among people’s abilities to handle fluid and flexible work conditions. We elaborate on the notion of "liminality" to denote a particular element of flexible work conditions, which consists of continuous movement among assignments and of simultaneous engagement with several organizations. Based on qualitative and interpretative research involving a combination of interviews, diaries, and workshops, this article identifies three levels of specific "liminality competence" that mobile project workers develop to deal with liminality at work.