2APL (A Practical Agent Programming Language) is a modular BDI-based programming language that supports the development of multi-agent systems. 2APL provides a rich set of programming constructs allowing direct implementation of concepts such as beliefs, declarative goals, actions, plans, events, and reasoning rules. The reasoning rules allow run-time selection and generation of plans based on declarative goals, received events and messages, and failed plans. 2APL can be used to implement muti-agent systems consisting of software agents with reactive as well as pro-active behaviours.