This book constitutes the post-conference proceedings of the International Workshop on Ontology, Conceptualization and Epistemology for Information Systems, Software Engineering and Service Sciences (ONTOSE 2010), held at the CAiSE 2010 conference in Hammamet, Tunisia, June, 2010. The 10 papers presented in this volume were carefully revised and selected from 25 submissions. They are grouped in sections on enterprise and service architectures, ontology applications, ontology visualization and query expansion, and ontologies for services.