Comunicational interaction of agents can be described at different levels of complexity and abstraction: The lowest level introduces possible message types. The protocol level links messages together to create communicational contexts. The decision layer consists of all (usually domaindependent) criteria and measurements to rank and compare different suggestions and proposals arising during a negotiation. The usage of these criteria determines an agent’s actual decisions. Within the framework of the protocol these decisions compose the negotiation strategy of an agent. The cooperative behavior can be described by considering the society of all interacting agents and it emerges from the interdependencies of the different negotiation strategies of the agents. This interaction model is exemplified by the problem of appointment scheduling. COSMA agents (COoperative Schedule Management Agents) are designed to act as personal assistants to maintain their user’s calendar. They are provided with competence for negotiating about scheduling appointments with other COSMAs. COSMA is an ongoing research project and several features are not yet fully developed. Therefore, throughout the whole paper we will also discuss future extensions to the system.