APRIL [MCabe and Clark, 1994] and MAIL [Haugeneder et al., 1994] are two languages for developing multi-agent applications that were developed as part of the ESPRIT project IMAGINE [Haugeneder, 1994]. The two languages are intended to fulfill quite different roles. APRIL was designed to provide the core features required to realise most agent architectures and systems. Thus APRIL provides facilities for multi-tasking (via processes, which are treated as first-class objects, and a UNIX-like fork facility), communication (with powerful message-passing facilities supporting network-transparent agent-to-agent links); and pattern matching and symbolic processing capabilities. The generality of APRIL comes at the expense of powerful abstractions - an APRIL system builder must implement an agent or system architecture from scratch using APRIL's primitives. In contrast, the MAIL language provides a rich collection of pre-defined abstractions, including plans and multi-agent plans. APRIL was originally envisaged as the implementation language for MAIL. The MAIL system has been used to implement several prototype multi-agent systems, including an urban traffic management scenario [Haugeneder and Steiner, 1994].