This paper compares two separately developed systems for monitoring activities related to business contracts, describes how we integrated them and exploits the lessons learned from this process to identify a core set of requirements for a Business Contract Language (BCL). Concepts in BCL needed for contract monitoring include: the expression of coordinated concurrent actions; obliged, permitted and prohibited actions; rich timeliness expressions such as sliding windows; delegations; policy violations; contract termination/renewal conditions and reference to external data/events such as change in interest rates. The aim of BCL is to provide sufficient expressive power to describe contracts, including conditions which specify real-time processing, yet be simple enough to retain a human-oriented style for expressing contracts.