This paper presents a novel approach to inter-organizational workflow cooperation. Our goal is to provide support for organizations which are involved in a shared but not pre-modeled cooperative workflow across organizational boundaries. Our approach allows for partial visibility of workflows and their resources, thus providing powerful ways for inter-organizational workflow configuration. Varying degrees of visibility of workflows enable organizations to retain required levels of privacy and security of internal workflows. Our presented view concept provides a high degree of flexibility for participating organizations, since internal structures of collaborative workflows may be adapted without changes in the inter-organizational workflows. Furthermore, we provide workflow participants with the freedom to change their workflows without changing their roles in the cooperation. This increases flexibility and is an important step to increase e#ciency as well as reduction in costs for inter-organizational workflows. The presented approach is inspired by the Service-oriented Architecture (SOA). Accordingly, our approach consists of three steps: workflow advertisement, workflow interconnection, and workflow cooperation.