This book presents an overview of two approaches to software engineering - formal methods and object-oriented techniques - and by extracting the best aspects of each demonstrates how better and safer software is being developed. Three main strands of research are identified and discussed: the application of formal techniques to object technology; the extension of formal methods with object-oriented concepts; and the formal foundations of object technology. Examples of each approach are included and areas such as concurrency and real time, which are especially important in the development of large scale, distributed and safety critical systems, are addressed. By focusing on these two, previously independent, techniques and illustrating how their merger is resulting in the development of tools which are essential to the development of large scale software the editors of this book have provided valuable coverage of this rapidly developing and important area.