This paper proposes an architectural model to facilitate the design of component-based groupware systems. This architectural model has been defined based on (1) three pre-defined component types, (2) a refinement strategy that relies on these component types, (3) the identification of layers of collaboration concerns, and (4) rules for the coupling and distribution of the components that implement these concerns. Our architectural model is beneficial for controlling the complexity of the development process, since it gives concrete guidance on the concerns to be considered and decomposition disciplines to be applied in each development step. The paper illustrates the application of this architectural model with an example of an electronic voting system.