In component-based software systems, the basic building block is the component, and applications are built as component compositions. 'Dynamic reconfiguration' in such systems is defined as the ability to replace individual components at runtime, or to change the compositional topology by adding/removing components and/or changing the patterns of their interconnection. A 'quiescence service' supports dynamic reconfiguration by pushing a system into a stable state in which such changes can be safely made. It is thus a key enabler of dynamic reconfiguration. The authors present the design of a quiescence service, which has been implemented for the OpenCOM component-based programming platform. It is argued that this design shows significant advances over the state of the art in quiescence support for component-based systems. In particular, it minimises programmer overhead and system disruption, and efficiently supports a large class of systems without imposing architectural constraints.