This paper describes an environment for interactive configuration management of software for distributed applications and services. Configuration management involves creating the components which form a distributed system; allocating these components to physical nodes and binding the interfaces of the components to each other or to existing services. Components and their required and provided interfaces are represented and accessible in the system-wide domain structure. We describe a graphical configuration environment, based on the Darwin configuration language, which is used to create the required configurations and maintain the configuration structure as part of the overall systems management infrastructure. The paper describes a simple example to show how a system can be initially constructed and subsequently reconfigured at run-time without shutting down the system.