Although several real multimodal systems have been built, their development still remains a difficult task. In this paper we address this problem of development of multimodal interfaces by describing a component-based approach, called ICARE, for rapidly developing multimodal interfaces. ICARE stands for Interaction-CARE (Complementarity Assignment Redundancy Equivalence). Our component-based approach relies on two types of software components. Firstly ICARE elementary components include Device components and Interaction Language components that enable us to develop pure modalities. The second type of components, called Composition components, define combined usages of modalities. Reusing and assembling ICARE components enable rapid development of multimodal interfaces. We have developed several multimodal systems using ICARE and we illustrate the discussion using one of them: the FACET simulator of the Rafale French military plane cockpit.