This paper presents a model-based approach to support service creation. In this approach, services are assumed to be created from (available) software components. The creation process may involve multiple design steps in which the requested service is repeatedly decomposed into more detailed functional parts, until these parts can be mapped onto software components. A modeling language is used to express and enable analysis of the resulting designs, in particular the behavior aspects. Methods are needed to verify the correctness of each design step. A technique called behavior refinement is introduced to assess the conformance relation between an abstract behavior and a more concrete (detailed) behavior. This technique is based on the application of abstraction rules to determine the abstraction of the concrete behavior, such that the obtained abstraction can be compared to the original abstract behavior. The application of this refinement technique throughout the creation process enforces the correctness of the created service.