—The dynamic composition of existing services into new services is at the core of service-oriented computing. The objective of FRESCO (Foundational Research on Service Composition) is to develop a framework that service providers can use in order to model, develop, and execute composite services. The FRESCO framework will include conceptual tools, such as models for service composition and aggregation. The framework will also include technology elements, such as an integrated development environment and specific components of the infrastructure for service execution. A methodology will be given for the use of the FRESCO framework in the development of composite service solutions. In this paper, we describe the main aspects of the approach to service composition adopted in FRESCO.