Book excerpt: This book constitutes the joint refereed proceedings of nine international workshops held as part of OTM 2005 in Agia Napa, Cyprus in October/November 2005.The 145 revised full papers presented were carefully reviewed and selected from a total of 268 submissions. Topics addressed are agents, Web services and ontologies merging (AWeSOMe 2005), context-aware mobile systems (CAMS 2005), grid computing and its application to data analysis (GADA 2005), inter-organizational systems and interoperability of enterprise software and applications (MIOS+INTEROP 2005), object-role modeling (ORM 2005), a PHD symposium (PhDS 2005), semantic-based geographical information systems (SeBGIS 2005), Web semantics (SWWS 2005), and ontologies, semantics and e-learning (WOSE 2005).