Global competition among today’s enterprises forces their business processes to evolve constantly, leading to changes in corresponding Web-based application systems. Most existing approaches that extend the traditional software engineering to develop Web-based application systems are based on object-oriented methods. Such methods emphasize modeling individual object behaviors instead of system behavior. This chapter proposes the Business Process-Based Methodology (BPBM) for developing such systems. It uses a business process as a unified conceptual framework for analyzing relationships between a business process and associated business objects and for identifying business activities and designing object-oriented components called business components. We propose measures for coupling and cohesion measurement in order to ensure that these business components enable the potential reusability. These business components can more clearly represent semantic system behaviors than linkages of individual object behaviors. A change made to one business process impacts some encapsulated atomic components within the respective business component without affecting other parts of the system. A business component is divided into parts suitable for implementation of multitier Web-based application systems.