Based on a practical presentation of the fundamental concepts of object-oriented modeling, it is explained that a new perspective is necessary for sustainable application development in the future. The object-oriented development process is illuminated in its professional and technical dimensions. A comprehensible guiding concept for system development, using the metaphor of tools and materials, is introduced. Object orientation influences not only programming and project strategy but also has implications for the developer organization. These considerations are supplemented by assessments of the short- and long-term economic viability of an object-oriented approach. A separate chapter presents detailed proposals for an implementation strategy tailored to the needs of commercial data processing.