Revision with unchanged content. In this book we define a methodology for the semi-automated aggregation and adaptation of Web services capable of suitably overcoming semantic and behaviour mismatches in view of business process integration within and across organisational boundaries. We tackle the aggregation and adaptation of services described by service contracts, which consist of signature (WSDL), ontology information (OWL), and behaviour specification (YAWL). We first describe an aggregation technique that automatically generates contracts of composite services satisfying (behavioural) client requests from a registry of service contracts. Further on, we present a behaviour-aware adaptation technique that supports the customisation of services to fulfil client requests. The adaptation technique can be used to adapt the behaviour of services to satisfy both functional and behavioural requests. We support the generation of service contracts from real-world service descriptions by introducing a pattern-based compositional translator for the automated generation of YAWL workflows from BPEL business processes. In this way, we pave the way for the formal analysis, aggregation, and adaptation of BPEL processes.