Appointment scheduling is a problem faced daily by many individuals and organizations. Cooperating agent systems have been developed to partially automate this task. In order to extend the circle of participants as far as possible we advocate the use of natural language transmitted by email. We demonstrate COSMA, a fully implemented German language server for existing appointment scheduling agent systems. COSMA can cope with multiple dialogues in parallel, and accounts for differences in dialogue behaviour between human and machine agents. 1 Motivation Appointment scheduling is a problem faced daily by many individuals and organizations, and typically solved using communication in natural language (NL) by phone, fax or by mail. In general, cooperative interaction between several participants is required. Systems available on the market allow for calendar and contact management. However, as (Busemann and Merget, 1995) point out in a market survey, all planning and scheduling activity r...