This paper has provided an overview of the field of object-oriented programming. After presenting a historical perspective and some major achievements in the field, four research directions were introduced: technologies integration, software components, distributed programming, and new paradigms. In general there is a need to continue research in traditional areas: (1) as computer systems become more and more complex, there is a need to further develop the work on architecture and design; (2) to support the development of complex systems, there is a need for better languages, environments, and tools; (3) foundations in the form of the conceptual framework and other theories must be extended to enhance the means for modeling and formal analysis, as well as for understanding future computer systems.