FOIS is the flagship conference of the International Association for Ontology and its Applications (IAOA). Its interdisciplinary research focus lies at the intersection of philosophical ontology, linguistics, logic, cognitive science, and computer science, as well as in the applications of ontological analysis to conceptual modeling, knowledge engineering, knowledge management, information-systems development, library and information science, scientific research, and semantic technologies in general. This volume presents the proceedings of FOIS 2018, held in Cape Town, South Africa, from 19-21 September. It was the 10th edition and 20th anniversary of the conference series. The volume contains 19 papers grouped into 4 sections: Foundations (7 papers), Agents and Properties (4 papers), Methods and Tools (4 papers), and Applications (4 papers). Regarding the applications of ontologies, a broad spectrum of areas is covered, including in particular biology and medicine, IoT, engineering and linguistics. Formal Ontology in Information Systems - Proceedings of the 10th International Conference (FOIS 2018) will be of interest to researchers from all disciplines with an interest in formal ontology.