This book constitutes the proceedings of the 18th International Conference on Conceptual Structures, ICCS 2010, held in Kuching, Sarawak, Malaysia, in July 2010. The 12 full papers and 6 posters presented were carefully reviewed and selected from 36 submissions. The volume also contains 5 invited talks. Originally centered around research on knowledge representation and reasoning with conceptual graphs, over the years ICCS has broadened its scopt to include innovations from a wider range of theories and related practices, among them other forms of graph-based formalisms like RDF or existential graphs, formal concept analysis, semantic Web technologies, ontologies, concept mapping and more.