The diffusion of service-oriented computing is today heavily influencing many software development and research activities. Despite this, service-oriented computing is a relatively new field, where many aspects still suffer from a lack of standardization. Also, the service-oriented approach is bringing together researchers from different communities or from organizations having developed their own solutions. This introduces the need for letting all these people communicate with each other using a common language and a common understanding of the technologies they are using or building. This paper proposes a conceptual model that describes actors, activities and entities involved in a service-oriented scenario and the relationships between them. While being created for a European project, the model is easily adaptable to address the needs of any other service-oriented initiative.