In technical Research and Development (R&D) projects, a Life Cycle Assessment (LCA) of the technology under development is sometimes carried out. Particularly in inter-organisational R&D projects, the roles of LCAs tend to be unclear and arbitrary, and as a consequence, LCA work is not adequately designed for the needs of the project. There is a need for research on how to choose an appropriate role for LCA in such projects and how to plan LCA work accordingly. We have identified some possible roles of LCA in inter-organisational R&D projects and used experiences from LCA work in different such projects to identify four project characteristics that are decisive for what roles the LCA can have. The project characteristics are: (i) the project's potential influence on environmental impacts, (ii) the degrees of freedom available for the technical direction of the project, (iii) the project's potential to provide required input to the LCA, and (iv) access to relevant audiences for the LCA results. We discuss how evaluation of these project characteristics can help project commissioners, project managers and LCA practitioners to deliberately choose appropriate roles of LCA in inter-organisational R&D projects and plan projects for efficient use of LCA.