The book provides an introduction to software engineering for distributed systems. Concepts which are essential for the development of distributed programs are described in detail. It is shown how methods of software engineering for both non distributed and distributed programs can be combined in order to use the advantages of all these methods. The result is called "subject oriented programming". It combines asynchronous parallel processes, i.e. threads and object oriented concepts. This hybrid approach makes it easier to design and implement distributed software systems and therefore increases the efficiency of the software engineering process. The reuse of existing software in order to protect software investment is also considered in "subject orientedprogramming."