We propose a novel framework (LECAP) for the development of event-based applications. Our approach offers the following advantages over existing approaches: 1) it supports a while-parallel language, 2) the reasoning allows a dynamic (instead of static) binding of programs to events, 3) it is oriented towards stepwise development of systems, and 4) the underlying logic supports the composition of specifications. The event based architectural style has been recognized as fostering the development of large-scale and complex systems by loosely coupling their components. It is therefore increasingly deployed in various environments such as middleware for mobile computing, message oriented middleware, integration frameworks, communication standards, and commercial toolkits. Current approaches to the development of event-based applications are ad hoc and do not support reasoning about their correctness. The LECAP approach is intended to solve this problem through a compositional and stepwise approach to specification and verification of event-based applications