This contribution describes a rule-based method for modeling business processes and workflows. Business rules are defined as statements about guidelines and restrictions with respect to states and processes in an organization. After introducing an extended Event-Condition-Action (ECA) notation, an approach for the refinement of business rules is developed in order to achieve a consistent decomposition of the business processes. Thus, ECA rules serve as an integration layer between different process modeling and (workflow) specification languages. Finally, we propose an architecture of a rule-oriented repository supporting the modeling and refinement process.