The complex nature of a home care (HC) situation induces an important need for cooperation between the health care professionals. But even if this need is sometimes evocated in reports on HC issues, it is more difficult to get precise knowledge on this cooperative activity, and, consequently, propositions for computerized HC organization and management systems. We did some researches on this topic area. Previous phases of work let us highlight the actual need for cooperation, and obtain precise information on the HC activity processes and data. In this paper, we focused on the integration of this cognitive knowledge on the design of a HC cooperation architecture. Different levels of requirements for the cooperative system are mentioned: coordination, communication of information, delegation of activity, integration of services and personal access to the tasks to perform. A description of the usefulness and use of the cognitive knowledge is proposed, the architecture design, modular, distributed, and able to integrate external services is presented, and the results of a validation test of the implemented prototype, performed with actual HC professionals in an evaluation laboratory are presented.