Organizations increasingly use forms of temporary organizing to achieve business goals. In the academic debate on temporary organizing the relationship between the temporary and the parent organization has so far remained underexposed. This paper uses modularity theory and the deployment strategy of the Dutch Armed Forces as a starting point to explore this relationship. Especially organizations that frequently participate in inter-organizational projects and contribute larger organizational elements to these temporary structures can benefit from the research findings. The results confirm that the so much desired plug-and-play character of a modular system is difficult to achieve in a social system, making it necessary for organizations to put extra effort in standardization, co-ordination and socialization capabilities.