In this chapter, we examined a few coexistence issues involved with running Notes/Domino 8.5 in a mixed environment with one or more previous releases. We began with a look at Notes client coexistence. We explained how to install two different versions of Notes on a workstation, and discussed potential issues with calendaring and scheduling in a multi-release environment. We concluded with a discussion of Domino 8.5 server coexistence, including features such as the Domino Directory, ODS, Domino Web Access, DDM, and ID files.