In recent years, 3D content has become more and more widespread and have been made available in a plethora of online repositories. A systematic and formal approach for capturing and representing related knowledge/information is needed to facilitate its reuse, its search and retrieval, and enable the demonstration of useful applications. In this paper we present the FOCUS K3D Coordination Action which aims to foster the comprehension, adoption and use of knowledge intensive technologies for coding and sharing 3D media content in consolidate and emerging application communities like Cultural Heritage & Archaeology, Medicine & Bioinformatics, Gaming & Simulation and CAD/CAE & Virtual Product Modelling.